Vintage Synth Repair

PS I found another problem right away.  I'd already tried socketing
all the Transistor arrays and replacing them since I've seen them be a
problem in the past and silicon is always suspect.  But all was the
same.  So I figured something must be open and sure enough checked the
3% 1.87K resistor first and it's open. hehe. I knew that wasn't going
to be the pop though probably but it did allow me to at least scale
the filter so it sounds right and the slider doesn't respond abruptly.  

Ok...after clearing that up...it looks like (after finally digesting a
few more parts of the fuzzy diagram) that it's clean up to the inputs
of the output of the dual FET but then the filter output op amp all
the sudden has the big pop signal on it.  And I finally see that it's
a 1458 not a 301 so it could be cross talk I suppose.  Replace and
find little changed though.  With all adjusted though it's..almost
tolerable but that blasted pop when the keys are hit is still there to
where it bugs me.  I haven't worked on axxe before.  Is that just a
characteristic part of the sound? -Bob