Vintage Synth Repair

Hello,
I'm having a few small issues with my Polymoog Keyboard... For some 
reason, the 2 oscillators became detuned. There isn't a pot to 
control the second oscillator that I can find. Is there a board 
mounted pot that adjusts that? Also, it's starting to make an arcing 
noise after it's been on 15 minutes or so. It's not the master power 
switch that's doing it, but it kind of has that sound... That loud 
intermittent bursting noise. And finally, the output is very quiet. I 
have to turn everything all the way up (and on my amp) to hear it. 
This problem can be fixed by unplugging one of the ribbons off the 
board of what I think might contain the amp (it's the board where the 
buttons are mounted above the kb. is that the amp?). When this ribbon 
is unplugged, the sound gets louder but loses most filters. Then the 
volume pot works backwards (10=0, 0=10). Has anyone experienced any 
of these problems?
Thanks,
Mike