Hi bgott,

I just went through this exact issue with a VS232 I bought on CL.

I had to do three things to fix the problem.

First, one of the power supply capacitors for the +15 volts for the chorus circuit had a broken solder joint. Check the solder joints on C17 and C18. A bad solder joint here caused a TON of noise to get coupled into the amplifier section, (whether the chorus was turned on or off).

Second, the high frequency noise had caused two resisters to get burned out in the the power amp section.  These are 1/2 watt 10 ohm resisters, R10 and R18. Check those and replace them if they are burned.

That solved 95% of the noise from the chorus circuit.

The last thing I did was to add two 0.1uF ceramic capacitors to decouple the power supply pins of the two chips that are part of the analog delay for the chorus, IC4 and IC7.  For IC4, I soldered the 0.1uF capacitor between pins  1 and 5, for IC7 between pins 1 and 3.  I was using a oscilloscope, and I could see a lot of voltage spike noise being generated from the clock signals between these two chips.  Adding the 0.1uF decoupling caps got rid of most of the remaining noise.

Please let us know if any of this helped and if you have had any further luck repairing your amp!