Microwave 2 OS Version 2.09: Knob trouble, cannot change properly, bouncing

Hi

I have a Microwave 2 here with OS Version 2.09. It wasn't used for quite some time and I was planning to sell it.. but when I tried it out, I had problems with the knobs. The values I tried to set were bouncing between shorter ranges, like 10-14 only, then I tried to move a larger range, then I just had another smaller range only... like 24-27 or so. This happens with the large red knob as well as the smaller black ones.
Is this a controller problem? Do I need to change the controllers? I do have some background in electronics and can do soldering... but IF the controllers are the cause: where do I get replacement parts?
Or is this an OS issue?

best
Henning

Turn the encoder for a few minutes. This often helps. It is not a software problem, it is an encoder problem. The encoders are made by Alps. But you may try cleaning their contacts: pics.studiorepair.de/Waldorf/IMG_7646.JPG