Vintage Synth Repair

So let's try a different approach here.

How exactly does the whole CV memory circuit work? The CV is stored by
charging C8. As long as a key is held nothing happens as far as the memory
function goes. If the key is released Q7 is turned off so C8 cannot
discharge; now we're in the memory "function". Q8 and A1B are the buffer.

It would be interesting to learn more about the exact behaviour of the
problem. Does the semitone change happen immediately and at once or
gradually? Does the note then stay at the same pitch afterwards or does it
continue moving upward??

Depending on that information I could make a better guess.