Discussion about the Korg PolySix synthesizer

Just got a Polysix in with some bizarre symptoms. It had an old battery
in it that looked like it had just started to leak. Only a couple of
traces had some black spots and still checked out okay with an ohmmeter.
I put in a cr2032 and diode and it is saving patches okay. It's not
until I twiddle some knobs that things start to get weird. Here is what
works: Output, Bend, Tune, VCO, VCA, Arpeggiator, Key Assign, Programmer
sections all OK. Problem sections: MG, VCF, EG, Effects. By Section: MG
- Frequency, Delay and Mod work, but Level seems to be controlling VCF
Cutoff, not modulation intensity. VCF - Cutoff does nothing, Resonance
works when set between 5 and 10, but seems to control Attack when set
between 0 and 5, EG Intensity does nothing, KBD Track works. EG - Attack
does nothing, Decay works, but in reverse, as if EG Intensity is in the
negative range. Release works between 5 and 10 but seems to do nothing
between 0 and 5. Effects - switch works, but Intensity does nothing.  
It would seem the D/A is having serious problems, and I can't get LEDs 1
and 8 to light up during the reset procedure. I get 1 and 5. I wish the
service manual had some voltages to measure, instead of just watching
lights. The +/-15 and +/-5v supplies look good. Anybody have ideas where
to start debugging this? I have a scope and multimeter, but no logic
analyzer. Thanks for any assistance you can provide. Don B.


[Non-text portions of this message have been removed]