Vintage Synth Repair

Hello, all.  The sample and hold on my Octave Cat suddenly will not
respond properly to 
respective pot information.  For instance, the VCO sample and hold
controls will now only 
tune the oscillators.  I've checked the socketed IC's in the S/H
circuit...they seem ok.  Is 
there a multiplexer for the S/H pot data that could be the culprit? 
If so I couldn't really 
identify it from the schematic.  Or is the problem related to the
sample and hold circuit 
not receiving a timing signal from the LFO?  Thanks in advance for
any tips. --Stephen 
Nichols