here at old crow's site,
http://www.oldcrows.net/~oldcrow/synth/tips.txt he discusses at pretty good length the importance of various capacitor purposes within synthesizers, particularly decoupling capacitors. For those he mentions that many synths have a plethora of .1uF caps all around circuits, and that they serve to keep a lot of noise out, such as high frequency noise.
In the polysix circuits, there are lots of .01uF, not .1uF. I'm not familiar yet enough with circuit theory to say wether or not those are the decoupling caps for the polysix. Can someone tell me?
My high pitch (and i call it pitch because it's audio range) noise that happens once in a while, is seeming likely to me to be a cap issue somewhere. I'm hesitant to start recapping things without having more of a target. Though i suppose it couldn't hurt to do the two big power ones and the five or six other small ones that are on the same power board.