Patches and discussion for Ensoniq VFX family

A short time ago the display of my SD-1 32 showed something like
"battery voltage low". Also it was out of tune and all the voice have
LFO modulation (even if the modulation wheel is at the lowest
position). So I replaced the battery (I am a technician) But it didn't
solve the problem. I checked all the analog values through the
testpage and they are all wrong (about twice as low as they should
be). I now am suspecting the circuit around the 4051 and opamp ; this
circuit collectes the analog values and transfers them to the A/D
converter inside a Processorchip.
Has anybody had the same problem ?

Greetings from Michel