G'day - I hope someone on here is familiar with the workings of Hammond Electronic organs - about 45 yr.old!

I could get photos IF someone reckons they might be able to help.

It is a two keyboard [upper and lower!] with presets, and slide bars to adjust the sound you wish to produce. Also has an octave of foot pedals - bass.  I am not the organist, but have done a bit of cleaning of contacts where multi wire connections attach to electronic boards.

This cleaning process seemed to help when we had some distortion [I think - it was some time ago!] but now it has another problem.

It is OK when turned on, everything works as it should, upper, lower and bass pedals.- Any setting changes all work OK.

Then after about 20 minutes, the upper keyboard looses volume and distorts slightly as it does.

It is used in our church, and we have found that by turning it off when not actually being played, we can avoid the problem. But that is a nuisance, to say the least.

If it was a 45 yr old car engine, with a carby, spark plugs, distributor and breaker points, I would say it was a spark coil breaking down when it warmed up!

Any help would be greatly appreciated.