Fender Twin Reverb w. Master Volume: terrible distortions

[kka]

Reading this thread I missed out on the date of the last sweet tone. Was it, maybe, before the some mysterious mod..?

My customer has not played this amp in 1-2 years. Before then he said it sounded "better" but not great. I assume that some parts just were on their way out like the filter caps for starters. After I have replaced them we'll listen in again. I might replace all other caps next if necessary.