National HRO 500 synthesizer instability possible fix band switch help for amateur operator in Japan

Synth instability. Just taping the side of the receiver it will go out of lock.
Just rotating the tuning knob - it will go out of lock.
What is microphonic?
I figured it was the varicap.
Upon a good inspection we find that the HF oscillator is tuned by a 3 ganged variable capacitor
which is right below the variable capacitor tuning the Spectrum Generator.
These move in lock step and are coupled via a tuning string.
The variable capacitor below and sitting on the deck of the receiver and mechanically coupled to the synth reduction gear is WIRED DIRECTLY to the band switch via heavy 14 or 16 gauge wire.
I would think this would be problematic as this puts stresses on the band switch and that any
mechanical displacement thru the case will cause a direct deflection of the plates in the
variable capacitor and the band switch
This seems like a very bad design idea and I think I will remove the 16 gauge wire and replace
it with flexible wire and see how that goes.
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Also of note I changed the 7.5 and 5 volt Zener diodes
and the 47 ohm and 100 ohm resistors feeding these zener diodes
were way high - the 100 ohm resistor was about 325 ohms and the 47 ohm one
watt resistor was about 100 ohms.
Alas all this work on the power supply did not make that much difference.

[@dfpolitowski2]

Not knowing a lot about the workings of a radio, to restore it, I just shotgun most of it. And have discovered the best way to do this is to have another unmolested or just a working rig of the same model next to me to be my guide together with a schematic drawing.

[@macster11]

Love, hate, ? I can hear it in your voice! Ready to punt?