I replace both tubes on the channel that redplated.
I replaces all four 10ohm resistors on the output tubes.
I cleaned up the wiring a bit.
Powered it up and there is definitely something awry.
Swapped signal source from side to side - issue persists
Swapped output tubes from side to side - issue persists.
Swapped center drive tube with one to the left - issue persists.
I thought it could be C1/C2 - swapped them from side to side - issue persists.
At this point I am not sure what I should check.
So far I have limited my measurements to the driver board starting with Pins 2 and 7 of V2.
I apologize for the size of these images, it is late and I do not have time to resize.
Yellow trace is left channel, white trace is right
V2 Pin2 & Pin7
V2 Pin1 & Pin6
This is the signal after C1 & C2
V1 Pin2 & V3 Pin2
V1 Pin1 & V3 Pin1
V1 Pin7 & V3 Pin7
V1 Pin6 & V3 Pin6
NFB Left & NFB Right