And voila, output was working. That cold solder was also one of the reasons for a “kind of” distorted output. But playing all six voices I found, that two voices were out of adjustment in volume and resonance. Ok, I thought, lets calibrate all voices, but that wasn´t successfull in the first instance. Some potentiometer had a strange behaviour, something like (guess what?) cold solder joints. After fixing these cold solder joints all six voices sounding great and I could go ahead with cleaning all the rest of the switches and potentiometer. Tactiles were ok, so no replacement here. Then I took a look to the keyboard and (ooooh, nooooo) I found out, that someone before me had scratched the contacts and scratched off the surface protection.