For both, cleaning the contacts and replacing the key bushings I had to disassemble the whole keyboard. While I was in here I removed some rust and I cleaned/washed the keys. After such a long time I don´t want to know, what that dirt is about. Now it's clean and safe and it can be played again without getting sick ;)
Someone worked on this Arp before. It already hat a new psu, new caps and faders were cleaned. Not very well. So I did some improved cleaning on some faders/sliders. I also cleaned the jacks on the back, the housing and -of course- the frontpanel.
Last but not least there was some very high frequency going on in the resonance. I fixed that by calibrating the synthesizer.
Now its future proofed for the next musicproduction or even for a live performance.