Discussion about the Korg PolySix synthesizer

I am working on a Korg Polysix with the usual tuning problems.  I replaced the 
photo coupler with a VACtrol and resistor mod and still  unable to tune 
keyboard. The high tuning control, VR2, seems  to do nothing. I have tried 
different resistor values with the VACtrol  mod and still have tuning problems 
with the high end of the scale. TIME  CRITICAL repair and going out of my 
mind!(BTW- no battery  corrosion at all!)KLM367 aligned perfectly, KLM 366 board 
is  new production. PLEASE HELP!!! Thanks in advance for your  time.

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