Grundig Ocean Boy Tuning reduction gearbox fix
 

I found a reliable workaround to resolve a grating problem with the tuning drive reduction gearbox found in Grundig Ocean Boy 820 International (1980s transistor set). If you find the same problem you could try my solution:

The tuning reduction is done in a compact plastic reduction gearbox.
The set I was fixing had a horrible grating/cogging feel at one end of the scale.
The problem also occurred across the whole tuning scale if the set was tilted forwards. The problem disappeared completely if the set was tilted backwards.

The gearbox can be removed from the set (3 larger screws) and the housing of the gearbox can be separated (3 smaller screws) but the cord pinion limits the extent to which it can be opened. On my example the cord pinion was stuck on solidly, gentle prizing did not move it. I decided not to risk damaging the pinion. I could see into the gearbox through the small separation gap but could not see anything causing the problem, all gear teeth looked OK. Lubrication was present and not dried out.
I found that the problem did not occur if the gearbox housing was slightly open. So my workaround was to insert 3 x small m2.5 washers between the two gearbox cover halves, secured by the 3 small screws on re-assembly.
This fixed the problem completely, no need to disassemble the gearbox.

Likely cause could have been impact to the tuning control from outside the unit (shipping or drop or other crush event) or aging distortion of some gear parts.

Best Regards
Chris

Re: Grundig Ocean Boy Tuning reduction gearbox fix
 

One of those great to know fixes that is now happily in the public domain. Or, super fix, thanks for telling us.