Vintage Synth Repair

Hello,

Today I've found some time to chnage the S/H IC, after some weeks ago I
changed the capacitos. The result stills the same. I don't know how to
continue. It really seems there's any missfunction with the S/H circuit and
I changed the the complete S/H circuit and before the IC from D/A converter,
the IC from multiplexer and some follower op amps from the output of that
multiplexers. There's no success with it. Some voltage that control the
filter stills with the same problem and thaqt filters works very noisy. Any
suggestion?

Thanks,

Joan M.