Vintage Synth Repair

I just picked up a second ProSoloist (kind of third, if you count the 
ProDGX). This one sat in a closet for 40 years, then restored. 
Perfect condition. Except for one thing....

Both of the "Fuzz Guitar" presets behave oddly. It seems like they 
sort of "cycle through" slightly different waveforms. Sine, square, 
saw, etc. Abruptly, almost like someone reciting vowels. also, Fuzz 
Guitar 1 is kind of quiet, while Fuzz Guitar 2 is really loud.

Everything else is great.


Any suggestions?



Thanks,

Jim