Fender BXR 200 bass amp - DeltaComp problems

[Bishop]

I have a Fender BXR 200 bass combo that has an issue with the DeltaComp compression. When I press the button to turn it on, the volume of the amp jumps DRAMATICALLY, and it feeds back. If I turn the gain all the way down so it doesn't feed back it sounds thin and buzzy (the green compression light still seems to work). Turning the compression off I get a major POP. Works fine otherwise.

I found the schematic and was basically wondering if the little section at the top right of page 1 (Q1, Q2, U8B, etc.) is all there is to the DelatComp, or am I missing something? Is there a muting system for the switch I should be looking at? Any input would be great, thanks!

[52 Bill]

Yes, that's the compressor circuit there. If you are getting switching noise, check for dc voltage on the output of U8B. Also check Q1, Q2, CR1 and CR2.