[_Cosmic_]

You must go slowly and delicately at all stages of the repair as you will not be able to get these parts again.

The next task (the most difficult) is to gain access to the inside of the brown plastic casing whilst inflicting the least amount of damage possible. The aim is to split it into two halves. They are held together by very small round ball-like clips and also on one side by two round plastic posts that are held in place by heat welding the surrounding plastic of the casing to the posts.

There are two of them on one side, where the ring terminals are, and there are plastic clips on the opposite side. On the first one I repaired I used heat from a soldering iron to try and release the post but ended up plunging the iron bit right through the casing and unintentionally making an unnecessarily large hole in it. I wasn't expecting the iron to go through so easily, it was like a hot knife through butter. So be very careful if you try to un-weld the casing this way. You can see the hole in one of the images. Luckily it didn't damage anything. My second repair was much better!
You need to try and prize the two halves apart. If you are lucky they might just prize apart from the clips simply using a small flat head screwdriver. Go slowly and cautiously and you should be able to take it apart. It will probably ping but be very careful because the two metal ring connections are anchored by the posts. Try very hard not to damage them.

When you have the unit in halves don't try to remove anything straight away.
inspect the terminals, one is soldered to the metal grill and the other goes to the copper film strip. Take photos so you can reassemble it again.
If you have got this far this is a great success and you have done very well...
Here's some photos so you know what to expect.

My next post will go through what you will encounter when you are inside, and why the units always eventually fail given time.