Discussion about the Korg PolySix synthesizer

Well, after a bit more troubleshooting, I discovered another bad trace
from the processor to somewhere. Once I repaired that, the programmer
started working *almost* properly. The Bank B and Program 2 lights
ALWAYS stay on, but I can select the other banks and programs no
problem now. Some of the programs appear to be blank or possibly not
working, but at least I'm getting somewhere!

My next big issue seems to be that the sub oscillator, and octave
selector switch don't seem to work. Sometimes the waveform selector
will work, and other times not. All the traces seem to be good on the
control board... I've cleaned the switches with contact cleaner, and
still nothing. 

Are these controls related to the corrosion-damage-zone?

I have not yet replaced the topmost 7408 nor the resistor array, as
they seem to be okay. Maybe I will do the 7408 just to be sure.