Thanks show case it can helps!!
Today I went through various cases with distortion:
Oxidation on switches and pots
Old and crackling solders
Group card unscrewed
On my ssl, all the modules have troubles with phase button! Every time you press phase there is a thin distortion that I can decrease a bit with the use of electrical contact cleaner. (I've noticed that it makes the button more harder to push...I'll probably have to use a lub to prevent on damage)
It's a long way...But in the end of the day I played with the desk....And that's so cool!!!