Discussion about the Korg PolySix synthesizer

Hello fellow Polysix lovers,

I am writing this in need of your help once again.

Few weeks ago my P6 started acting funny, it was detuned down for a whole octave and a half, and I noticed that master tune knob and mod wheels have no effect on the sound. I opened it up, saw if there are any loose cables, put it in test mode and back again, and when I returned it to "Normal", it was working as it should. But next time I powered it on (or the second time I can't remember), after some playing I noticed that the pitch was drifting. I tried the tune knob and mod wheels and realised that they are not working like that time before. This time, fiddling inside the P6 did not help.
If you have any suggestions what might be the problem, please write.

Thank you all in advance,
Milan