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Old 9th Jul 2020, 10:25 am   #1
Heatercathodeshort
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Default Ekco 19" table model 'Classic' T377 1961.

Ekco 19" table model T377 'Classic' 1961.

This is just a quickie one shot overhaul of the Ekco T377. It was the first 19" receiver released by Ekco incorporating the then new aluminised Mazda CME1901 semi squared off 114 degree CRT.

It has a long neck and had a very short life often requiring replacement after just two years or even less. The usual fault was an O/C cathode connection, a rapid fall off in emission or both. Back in the late 60's It was very rare to discover the original tube with any emission, a fact that had to be considered if you were buying receivers for overhaul and resale. Of course there is always the good one but they were rare indeed. The best part about the CME1901 is it's very fine screen phosphor developed by Mazda, first used with the CRM171 of 1953/4, capable of the best black and white pictures attainable.

The equivalent Mullard CRT of the same period was the AW47-90 another long neck first generation 19" tube. This enjoyed a very long service life and I have no doubt that if you come across one today, or the later short neck version the AW47-91 it will still have 100% emission unless that is, some idiot has bodged the mains dropper and over run the valves and tube heaters!

The CME 1901/2301 gave problems wherever it was used particularly in the Murphy Astra range of the same year together with the early Ultra Bermuda 19" and 23" range.

This example of the T377 had been carefully packed away for a number of years. It is extremely smart with it's bow fronted high gloss cabinet, gold trim and very neat presentation. I consider it to be one of Ekco's most stylish television receivers and there were quite a few in the Ekco range around that time. It's an Ultra Bermuda with class! The bowed implosion protection glass can be removed from the front without any disturbance to the cabinet or chassis. In the event, the tube probably required replacement before the glass needed cleaning!

With the Ekco on the bench the first thing noticed was a couple of twisted loose wires exiting through the cabinet back...MMMmmm!

With the back removed I had to laugh. They were directly connected to pins 1 & 8 of the Mazda tube. Presumably they had been connected to an external booster transformer there being no room in the inn or rather within the cabinet interior to fit one. The chassis is a very tight fit.

With any Ekcovision built between 1954 and 1963 the first item to check is the condition of the line output transformer plastic[?] enclosure/case. After a few years of use the one time clear material used for it's manufacture began to break down leading to arcing, burning and a potentially serious fire. This usually started on the top where the connections for the EHT rectifier, either the wired in U25 in earlier models or the B9A based U26 were located.

While viewing, the breakdown would hardly be noticed and the smoldering would continue after the end of transmission switch off. The smoldering and possible fire would continue through the night even after the plug had been withdrawn. An early clue to breakdown was a vinegar type smell, quite sickly and unpleasant but back in those 80 a day full strength Capstan cigarettes, nobody would have noticed.. The actual transformer windings were never damaged and a new case can be fabricated from sheet Paxolin or Perspex in fact any sheet material of good insulating properties, that is if it was caught early enough.

Fortunately the transformer is my example is in good condition with the main chassis neat and unmolested. I discovered the original heater supply wires and resoldered them back on the tube base. I snipped the mains filter and gave it the full mains. I'm very familiar with these Ekco chassis and knew there would be little if any harm done by my cowboy actions.

The heaters slowly built up but other than their pleasant glow the chassis was completely dead. A quick check along the mains dropper confirmed that one of the surge limiting sections feeding the rectifier was O/C. With a RS power section fitted the chassis livened up and I could hear a strong line whistle and a few crackles from the speaker.

Ekco by this time had returned to the valve H.T. rectifier trusting the much improved Mullard PY32/3. Mazda had not introduced a reliable H.T. rectifier to replace the unreliable U801 of 1951. This resulted in the manufacturers signed up to Mazda to use a metal rectifier, the Cossor 27SU or Mullard PY82 valves were also popular. Ekco decided to go the all metal way and employed the super reliable Automat metal rectifier in models produced between 1954 and about 1960.

Advancing the brilliance produced nothing on the screen and with all the lights turned off I could just make out what appeared to be a distorted mess about 2" high. As expected the tube was completely flat and after all these years, didn't take kindly to being exhumed. The chassis would require a complete waxie recap to bring it back to glory and a decent 19" tube.

The next move was to unbox the chassis. First the bottom inspection cover has to be removed [plastic turnbuckles similar to the back] A copper spring strip can then be unlocked and removed to release the side control panel. The channel selector knob can be removed from the tuner spindle by rotating until the grub screws are exposed and then loosened. There is a locking bar at the top of the cabinet similar to the earlier 17" T368 series that has to be unlocked before the cabinet can be pulled forward and lifted off. Clever!

The next move was to enter the tube store or rather the dusty loft above the garage. I always carry a can of 'Kill Anything that Moves' with me on these expeditions due to the fact that every biting and stinging insect known to man has decided to build it's web of horror in it's dark corners.

After a few false hopes I managed to find a clean example of the Mullard A47-14W, a later 19" tube with a shorter neck and a nice stylish dark gray screen filter. That will do nicely. I was confident about it's emission confirmed by my big black painted BERTHA tube tester.
[16]She has been a very long term friend. Pulled out of a skip so long ago I can't remember when. She has serviced many tubes over the decades and in her twilight years and with the aid of a three way switch and adapter, has been happy to serve the new boys on the block otherwise known as colour tubes.
[17]I'm going to cut out a lot of the Donkey work that I have covered in other Ekco 300 series overhauls that are very similar to this one.I was saved much of the frustration due to the high quality mica capacitors employed in the sound and vision I.F. amplifiers.

The chassis evolved from the original '3 Link' design of 1951 and continued in basic form until the PYE take over around 1963. The Ekcovision chassis is probably one of the most successful chassis designs of all time.

With the time consuming capacitor change, valve base and pot clean etc carried out it was time to install the replacement tube and hope for some visible results.

Switching on produces a super bright raster and applying some R.F. immediately produced a distorted test card. I must admit, knowing the Ekco, I expected this result and it only took a couple of minutes to square and center the picture and generally set it up. The picture produced takes some beating believe me.

A very long soak test proved the chassis to be very stable with that confident Ekco feel to it.

Pictures show the general presentation and off screen pictures of the Ekco T377.

The winds of change were just around the corner and that well known building opened in 1931 close to the Arterial Road at Southend on Sea would never be the same again. R.I.P. E.K. Cole. Your legend lives on.

Any questions? Please ask. John.
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Old 9th Jul 2020, 11:24 am   #2
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Default Re: Ekco 19" table model 'Classic' T377 1961.

Only mystery is why they still preferred the PY33 over a silicon rectifier.

We had an early Thorn 900 which lasted for years on the original CME1903 so I assume
this tube (probably the last unprotected type) might be better. Sometimes Ekco fitted
a card cover on the timebase pcb e.g. Dynatron TV38.
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Old 9th Jul 2020, 11:42 am   #3
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Default Re: Ekco 19" table model 'Classic' T377 1961.

John
A lovely looking set and brilliant picture, are you going to settle down and use this set?
The other thing that puzzles me coming to this years later, is how did Mazda manage to survive making such awful tubes, nowadays products with that sort of problem would be all over social media and Watchdog type programmes. Surely the TV manufacturers would not wanted to be associated with those problems and reputation damage or am I missing something?
Did Mazda solve the problems at some stage?
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Old 9th Jul 2020, 12:45 pm   #4
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Default Re: Ekco 19" table model 'Classic' T377 1961.

The silicon diode as an H.T. rectifier first saw the light in the Regentone ten series of receivers released around 1960. Two were mounted in series on a tag strip on the chassis frame. I believe they were STC types, very small about the size of a OA81. I seem to remember they had a screw fixing rather than solder. Either they were worried about the heat from a soldering iron or thought they may need to be replaced easily. They were reliable but you often discovered one shorted out. A single BY100 probably the best known diode of it's type would be fitted as a single replacement. The T377 Ekco used the very successful T368 chassis of the previous year that employed the PY32. Another possible reason is that the slightly later BY100 was quite expensive at the time, certainly more than a PY32 and it's holder, better the Devil you know!

The short life Mazda tubes certainly was a mystery. The early 2V triodes of the CRM class were very poor life wise and suffered from heater cathode shorts.

Around 1952 a Murphy dealer asked a question in the letters page of the Murphy Service News complaining of the very short life of the Mazda tubes. Murphy Radio replied saying that EDISWAN were aware of the problem but things would improve in the future. I don't think it did proved by the rapid loss of emission with the first 17" tetrode rectangular type CRM171.

The 14" tetrode circular tubes type CRM141/2 were also poor. Most of the ones I encountered were completely flat but they were getting on a bit at that time but the Mullard/GEC/Ferranti and Brimar tubes of the same age were usually 100%.

Things did get better around 1956 with the introduction of the CRM172 [Murphy V310] CRM93 [Ekco TMB272] and the CRM124 [Murphy V230]. The CME1402, CME1702 and CRM173 [Ekco T330] also enjoyed a good life.

With the arrival of the 110 degree CRT Mazda's offerings were the CME1703 and CME2103. This tubes gave brilliant pictures but it didn't last long. After a couple of years the emission would drop then stabilize resulting in a slightly fuzzy picture that lost it's sparkle. Customers never complained due to the gradual drop off but the tube required replacement during overhaul for resale.

The last Mazda tubes with a short life were the 'Gold Star' CME1903 tubes first used in the Thorn 900. I replaced very many that had simply disconnected their cathode connection. The symptoms were a very low brightness, focused raster with very slight signs of a picture. A tap on the neck usually had a very temporary cure. The sad fact was that these tubes gave outstanding pictures having the edge on the majority of the tube manufacturers.

Mazda valves were of very high quality with a very long service life but their rectifiers were another story that has been well covered in the past.

It seems quite amazing that the top British manufacturers of the time, EKCO, MURPHY and ULTRA put up with this state of affairs especially as such early tube failure looked badly against the brand concerned. It is also interesting to note that these three set makers were all victims of the 1961/62 slump that saw the collapse or merger of our best known set makers.

It's all water under the bridge now of course but a strange period in TV manufacturing history. luckily enough Mazda tubes have survived to keep us all busy!

My Great mate the late John Brown of Central Tubes always said the best combination was a Mullard gun and a Mazda screen. Regards, John.

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Old 9th Jul 2020, 4:08 pm   #5
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Default Re: Ekco 19" table model 'Classic' T377 1961.

The Ekco T377 "Classic" is really a T368 fitted with a 19" CRT.
introduced in 1960 the PY33 replaced the PY32. The later valve has an improved cathode coating which which reduced the forward voltage drop.
It's likely when the circuit design was signed off in 1960 the design team was not entirely decided whether to use the all new silicon diodes, much better wait and see how the other set makers fare with new device.

DFWB.
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Old 9th Jul 2020, 4:13 pm   #6
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Default Re: Ekco 19" table model 'Classic' T377 1961.

A very informative write up . I didn't know the slimline tubes with the longer neck were 114 degree I assumed they were 110.
You have worried me now as I have a Murphy Astra awaiting attention...!

Your set has the same type of chassis as my Dynatron I recently posted about. Mine has a degraded LOPT as you describe I really must sort it out I didn't realise they could smoulder like that!

Your Ekco really is a smart looking set with an excellent picture! Well done!

Rich
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Old 9th Jul 2020, 4:26 pm   #7
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Default Re: Ekco 19" table model 'Classic' T377 1961.

I really liked this chassis and cabinet style, the LOPTX housing was a problem but I never had a fire with one. The Mazda CRT’s, you summed up my thoughts, great picture when new but unreliable, I saw the same faults. We used Mullard for replacements, fit and forget.
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Old 9th Jul 2020, 4:42 pm   #8
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Default Re: Ekco 19" table model 'Classic' T377 1961.

Brimar made a 114 degree tube which had a short neck. The C19AH.

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Old 9th Jul 2020, 5:28 pm   #9
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Default Re: Ekco 19" table model 'Classic' T377 1961.

Quote:
Originally Posted by chriswood1900 View Post
John
A lovely looking set and brilliant picture, are you going to settle down and use this set?
Settle down! Settle down? Oh please! That creepy home for retired television repair guys comes to mind. Think of all those old guys wheeling perambulators around the gardens containing Bush TV22s..

I do enjoy a really super example of the 1953 15" Ekco TC196 console in my winter 'snug.' I recently constructed a trolley [Television Trolley thread] that can accommodate virtually any table model and might put it into good use by changing round a few receivers for a week or two, just to get the feel of viewing vintage receivers. The T337 is certainly a candidate.
Thanks for your interest. John.
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Old 9th Jul 2020, 5:41 pm   #10
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Default Re: Ekco 19" table model 'Classic' T377 1961.

I must admit that I always preferred the 19 and 23 inch CRTs to the 17 and 21 inch types - less "goldfish bowl" in appearance.

The Ekco T368 was just about the pinnacle of Ekco's VHF/405 only set electrical design and very easy to service - the whole cabinet lifts off.

I also used to prefer the "F" version (Fringe), with flywheel sync (and sometimes a better gated vision AGC system).

Ekco certainly were one of the best in terms of solid construction and performance - rather like Bush over the same period.

Concerning these unreliable Mazda CRTs - perhaps Ekco, Murphy and Ultra were tied into long term supply contracts with Ediswan/Siemens Ediswan/AEI? Things seemed to improve when AEI sold their consumer valves and CRTs division to Thorn Electrical Industries.
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Old 9th Jul 2020, 5:56 pm   #11
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Default Re: Ekco 19" table model 'Classic' T377 1961.

Quote:
Originally Posted by slidertogrid View Post
You have worried me now as I have a Murphy Astra awaiting attention...! Rich
Don't worry too much Rich, The original tube has probably been replaced possibly by a decent regun. Either that or you have the only remaining CME1901 with any emission. Any 19" unprotected tube will fit the Astra series.

I have a new Mullard A47-14W in my Astra that was generously given to me by another Forum member a good few years ago. [Thanks Tas]

Good luck with it and I hope the LOPT is serviceable. John.
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Old 9th Jul 2020, 5:59 pm   #12
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Default Re: Ekco 19" table model 'Classic' T377 1961.

John
Thanks for the insight into Mazda tubes, given their good start and rapid deterioration you have to wonder whether it was a problem with the coating of the cathode not maintaining emissions. Our first set at home was an Ekco T283 with 14" tube and from the age of 8 I became adept at tapping the tube neck through the cover with plastic rod kept by the set to deal with the heater cathode short!
We kept the set going for about 20 years with that technique.
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Old 9th Jul 2020, 8:08 pm   #13
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Default Re: Ekco 19" table model 'Classic' T377 1961.

Hi John,

That Ekco looks good! I’ve actually got a lovely little T368 here, picked it up from the NVCF in 2014, it had the severely decomposed LOPT housing, which I rebuilt with something that looked and smelled like Paxolin, the tube tested flat as a pancake on the old B&K, but actually came up quite well. There was also a nasty burn up to deal with in the frame stage, R72 had turned completely to ash, goodness knows what was holding it in shape, I poked it with a screwdriver and it fell to dust! The PCB was damaged under it too, it had become conductive and I had to cut out a big chunk of it. Despite the numerous problems the set came good and works very well, still a few little things to sort out, the metrosil is missing, and there was a slight line twitch on some pictures, oh, and the back cover fixings are missing too. Still doesn’t beat the TMB272 for picture quality!

If you’re interested here’s the thread on the sets almost restoration!

Regards
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Old 10th Jul 2020, 11:24 am   #14
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Default Re: Ekco 19" table model 'Classic' T377 1961.

Just a warning!
If the LOPT case is breaking down it must be sorted out. The problem is that when it is breaking down there is no obvious problem with the picture and the smoldering carries on after switch off. It's a dangerous situation.

Very many years ago [1967?]I visited a mate that had a TV sales and repair shop. We were chatting away and I was looking at the soak bench where the reconditioned receivers were awaiting new customers. I noticed that a Ferranti T1002 the 17" version of the Ekco T327 was making a slight frying noise. I brought this to his attention and the receiver was switched off pending further investigation.

About a week later I had a phone call from my mate to inform me that the offending Ferranti had been inadvertently sold to an elderly couple that lived in a local authority flat. Apparently they had received a phone call from the owner to inform him that the Ferranti had 'overheated' and could they pop round and see what could be done.

His shop was just along the road in the next High Street. Intrigued I went along with him to see what it was all about.

I knocked on the door to be greeted by the elderly chap and his wife that appeared to be calm and friendly. They invited us into the hall and it was then that I noticed a distinct 'bonfire' smell.

He pushed open the living room door and the sight that greeted us was astonishing. The room was completely sooted black. All that remained of the Ferranti was a few bits of burnt cabinet collapsed across the chassis. The tube had imploded sending glass across the room. The odd thing was the lace cover that was on top of the TV table was unharmed.

They had turned the TV off as usual the night before and removed the mains plug as most people used to do back then before retiring to bed and slept through all the incident.

Unknown to them the LOPT was smoldering that eventually led to a dangerous situation.
Fortunately they had closed the living room door resulting in air being severely restricted that resulted in a slow disintegration of the cabinet without actually bursting into flames.

The Council had just redecorated their flat and were quite OK about the incident. The odd thing was the couple accepted the situation and would you believe it they called at the shop a few weeks later and chose a reconditioned Ferguson 306T to replace the Ferranti.

They did have contents insurance that at least covered the damaged furniture.

How times have changed. You can imagine the claim that would be brought into action these days! Just take a bit of care and don't ignore symptoms that can lead to a disaster. John.
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Old 10th Jul 2020, 2:56 pm   #15
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Default Re: Ekco 19" table model 'Classic' T377 1961.

An excellent write up once again John. I expect you remember the 17" T370 that you helped me with 10 (yes 10!!!) years ago. The LOPT case in mine had all but disintegrated. Although the Mazda CRT was okay, it was by no means in its first flush of life and a couple of years ago, I managed to get hold of a new Mullard regun AW43 89 which I fitted to it and it really is a super performing set now.

I'm inclined to agree with Dazzlevision in this particular instance that in this style of cabinet, your 19" CRT has a more stylish look to it.

Thanks again for sharing the story.
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Old 10th Jul 2020, 2:58 pm   #16
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Default Re: Ekco 19" table model 'Classic' T377 1961.

Quote:
Originally Posted by Heatercathodeshort View Post

I have a new Mullard A47-14W in my Astra that was generously given to me by another Forum member a good few years ago. [Thanks Tas]
My pleasure John. Without wishing to go too O/T, did you sort out the falling EHT problem on the Murphy Astra as the set warmed up?
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Old 10th Jul 2020, 10:53 pm   #17
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Default Re: Ekco 19" table model 'Classic' T377 1961.

Hi John,
Thanks for another exciting escapade!

Quote:
Another possible reason is that the slightly later BY100 was quite expensive at the time, certainly more than a PY32 and it's holder, better the Devil you know!
It's hard to believe that a silicon diode, which we now think of as trivial cost wise, could be dearer than a valve & socket!
Still, it seems a bit odd that after a few years of using metal rectifiers, they reverted to a valve one.

One advantage of a valve rectifier is that it dissipates a very significant amount of heater power. In a series string, if the valve is replaced by a solid state device, that extra power still has to be dissipated in the mains dropper. I think the valve is much better able to handle this than the mains dropper!

One of the problems with my Pilot PT650 is they have pared the number of valves to the minimum. Consequently, the dropper has to dissipate nearly 40Watts of heat including the HT section! A valve rectifier would have helped spread the heat around the chassis a bit more.

I'm always amazed by the tales of the Mazda misery tubes! I can't believe set makers were tied into using them and could not go elsewhere. Not that Mullard were blameless either!

I'm convinced that our lack of attention to quality was the reason most British products were rapidly eclipsed by Japanese imports when they started coming into the country.

All part of the fascinating history of consumer electronics!

All the best
Nick
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Old 11th Jul 2020, 9:47 am   #18
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Default Re: Ekco 19" table model 'Classic' T377 1961.

This issue has always fascinated me. Those 3 major set manufacturers collectively would have had some clout! I find it difficult to comprehend that the poor reliability of Mazda CRTs was allowed to continue for so long, albeit Mazdas promise of it getting better, when it really didn’t.

Were those manufacturers complicit in this? The general opinion on initial picture quality, is that Mazda had the edge, was this their lever on continued sales? It would also be interesting to know the cost price per CRT to the manufacturers. We’re they cheaper than
Mullard?

We will probably never know!

Cheers. SimonT.
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Old 11th Jul 2020, 10:48 am   #19
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Default Re: Ekco 19" table model 'Classic' T377 1961.

One important component that has to be checked with the later Ekco T 368 and many subsequent models is the 27K 2watt resistor R45 on the Ekco cards connected between the H.T. line and the cathode circuit of the 6F23 video output valve.There should be 2.5v at this point.

When it reduces in value the symptoms are certainly odd. If the contrast is advanced to give the correct black/grey level the picture pulsates violently. Reducing or advancing the contrast either just too high or low for comfortable viewing, the pulsing ceases completely.

The first time I encountered this many years ago it took a while to work out what was happening. You may well still encounter it! John.
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Old 11th Jul 2020, 11:32 am   #20
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Default Re: Ekco 19" table model 'Classic' T377 1961.

Yes that 27k was a stock fault, a bit awkward to get at but I had a lot more dexterity then. I replaced them with a 3 watt dog bone type resistor, that stopped it happening again.
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