chasing an amp fault in this solid state Marshall

[pucho812]

So I am working on this Marshall vavestate bi-chorus. The clean channel works well and sounds great. The boost Channel is very low in volume.
I get the correct voltages on the tube and I do get the OD1 and OD2 switching. I got the gain pot working without issue. But after the tone stack, the contour pot and volume pot do not function. I have traced signals and I loose a lot of volume in the tone stack and it just gets progressively worse. I am not sure what is left to check. All of that is happening before any insert send and return and with the clean channel working as it should it leaves out the insert jacks as being a problem.

https://schematicheaven.net/marshallamps/stereochorusrev_2x80w_8280.pdf

 

[NoisyIndividual]

Make sure all the pots are ok and actually in circuit.
I had a smilar problem that confounded me until I realised several pots weren't actually in circuit.

Some odd corrosion event happened in storage I think.