Vintage Synth Repair

All,

I could use some help with my memorymoog plus.

I recently noticed that the Mod Wheel was no longer applying vibrato to
the oscillators.

At first, I thought that maybe a wire had broken loose.

But upon further investigation, I determined that the LFO Freq Mod of
OSCs 1, 2 and 3 was NOT working.

I DID verify that the LFO is working, by sending the signal to the
Filter and hearing the expected effect.

I was hoping it was a simple, internal connection issue so I went "under
the hood" and

disconnected/reconnected all of the data and signal cables, but it
didn't correct the problem.

I have the tech manual and schematics but I'm really not a tech.  More
of a tinker type.

I was hoping for some suggestions here on how to further troubleshoot
the problem myself  (if possible).

Any help or suggestions would be greatly appreciated.

BTW, I am in the DC area if you also have any referrals to a good,
qualified tech.

Thank you in advance.

-LOTS