[sdiy] OB8 question

[klosmon]

Hello-
I've dealt with a dozen or so of these, and while most can be repaired,
scaled & tuned to behave correctly, I've seen a few (like the one I'm
working on now) which have one voice which will fail to pass tune --
even though re-enabling the voice in page 2 shows the voice to be correct.

I've tried the voice board in another synth with the same problem, so
it's not the power supply or CPU board;  I've swapped out ALL the ICs on
the board (along with all the capacitors), and the problem still
remains.  I've measured the resistors & traced the tuning signal with a
scope -- everything appears normal, but that one voice still won't pass
tune.

Any ideas as to why this might be happening?

It wouldn't bother me so much, but I've seen it in several OB8s now, and 
would like to have some idea what's going on.

Thanks.

~GMM