Slightly Broken Moog Source (help?)

I bought a moog source off the internet a little while ago. The previous owner claimed it worked 100% except that it required “a 10 minute warmup” or else it would act “crazy”…I figured it might be the “crazy source” syndrome, and that I’d also probably be able to fix it myself.

So then I received it (it was properly packaged) and lo and behold, none of the keys triggered any sound (no matter what length of time I allowed for “warmup”)

I would like to fix this, but I don’t want to take it to a technician because I don’t want to spend the money, I believe in self-doing it, and I would like to learn.

I don’t believe it will be a difficult fix because:
(1) I am able to trigger sound via keyboard/CV,
(2) I am able to trigger sound by pressing the sample and hold button on the source without any external/CV action,
(3) ALL of the parameters work and the membrane is fully-functioning.

The only problem seems to be the lack of communication between the keys and the rest of the synth. I have already opened it up and tried checking the connections for the keyboard to see if they came loose during shipping, but no luck. The keys are all clean feeling and I am slightly skeptical that the problem is dirty contacts, but I may clean them for the hell of it.

ANY thoughts/advice on the matter would be very helpful and greatly appreciated.