Troubleshoot and repair Marshall Valvestate 8020?

[billyjack669]

I got this amp new for Christmas as a kid in the early 90s and blew it up in the early 2000s by running the instrument cable tip around my CRT television screen to make "cool noises" (until it stopped making sound.)

Last year I started a Reddit thread and got enough responses to get the clean channel back.
(Replacing R42 which was visibly damaged)

The boost channel is still completely silent.

I have a cheap scope and would be super happy to test and fix it with your guidance.  I can solder
  Thanks for reading!

VS8020 Schematic Link (Dr Tube's site)

[Jazz P Bass]

Use the scope on the output pins of each IC in the boost circuit.
Go down the line, left to right.