ok, pulled one side of r40 and reinstalled new cap in c26 now the high frequency oscillation is completely gone, but turning up the reverb level creates distortion/static sound.

Well I replaced c26 with a new capacitor of the same value, and replaced the other three on the board that were also the same value (only because I got a 100ct box from mouser).  Still noise persists unless I pull c26.

Ok I replaced IC1 (TL074) and resoldered the capacitor back in place (c26) and the noise came back.  Removing the capacitor (c26) again and the noise goes away.  I really appreciate the help so far but what can we try next to eliminate this noise. I think we are close.

Ok, pulling "C26" fixed the noise!!!!! Now "IC1" is a "TLO74CN" , are there any compatable alternative replacements? Having a hard time finding this part.  Thanks for everything you guys.

Ok how would I go about testing the opamps voltage pins? I have the schematic.

Ok, shorting the reverb return did not work.  Here are some pics of the board.

Thanks for all the help I will try it right away.

Also disconnecting the reverb completely did not change anything.

So you are talking about the rca jacks that go to the reverb?  If so the return one I need to connect a shorted plug to ie: inner conductor to outer shield?  Just wanted to clarify before attempting it.

ok here is the sound file, this one works.  the recording is with mic next to cabinet, power switch cycled on for ten seconds and back off all controls set to zero.

Well with all controls set to zero it produces a sound that is a bit like if you were to hold down a button on a touch tone phone.  It increases with volume, does it regardless of which channel, with or without a guitar plugged in.  If you even barely turn up the reverb control knob the volume of the "tone" gets so loud it is almost unbearable.  Yet you can still plug in an instrument and it plays fine just with an equally loud "tone".  When amp is powered off the sound kind of dies out with a warbled? sound? dont know how to better describe it.

I am working on a marshall vs 232 stereo chorus 2x12 all solid state amp.  Can't figure out the source of this strange noise.  I am attatching a zip file with a recording of the sound.  Never heard anything like this before.