Vintage Minimoog pitch problems--Keyboard circuit?

[udream]

Anyone ever experience this bizarre problem? If I hold down a key and press a higher key, the pitch raise almost a half semitone. Usually when you play legato, due to low note priority, only the low note will sound, but if I do that the low note is always 1/2 semitone sharp. If I release the higher key, the lower key plays its normal pitch. Fortunately, my old osc. board vintage minimoog has a CV/GATE input, so I can trigger the Mini via an external keyboard, such as the Roland SH-101. The pitch problem doesn't happen under those conditions, so I reason that the problem is with a component in the keyboard circuitry. Any thoughts?

[till]

As it isn't like this on my 1979 vintage Minimoog I own for decades, it is most likely some faulty contact or component. Maybe the keyboard S&H is not triggered or gone bad?