Minimoog synthesizer repair service. My customer wanted a complete review of his beloved Minimoog. A few keys didn't play properly, most of the knobs and switches scratched. And the audio output didn't work.
The keyboard electronics were completely corroded. The "bus bars" were oxidized, but were easy to clean again. The individual, small contact springs were a bit more difficult to clean. But in the end the entire keyboard and its connectors could be cleaned well.
The electrolytic capacitors, especially those from the power supply unit, were getting on in years. Here I have swapped all electrolytic capacitors that were not installed in the audio path. I measured the electrolytic capacitors in the audio path and exchanged them for high-quality audio electrolytic capacitors.
The potentiometers (rotary switches and switches) have not been cleaned thoroughly for a long time, if at all. This is a bit time-consuming, but it is worth it. Because this not only improves the tuning stability significantly. The filter also reacts more precisely.