Was playing my 1982 2203 yesterday, suddenly the notes startet to fade, they were still audible but lost some volume and low frequency hum start swelling up. I instantly walked to the amp and turned it off. I bought it from a tech who told me he had reformed the original filter caps, but the amp is completely stock including the tubes which are Yugoslawian EIs. Now I know that original filter caps are a disaster waiting to happen and I knew one day I'd have to change them. I am afraid to turn the amp back on, I'd rather have a tech swap caps and maybe even pop in some new tubes. Just curious what it could be? As said the notes suddenly became weaker and a low frequency hum started appearing, first quiet and then it gradually got louder, it felt like it was overtaking the notes volume. Hard to describe. It all happened maybe in the matter of 10 seconds before I walked over and flicked the standby and power off. @ampmadscientist Any clues? Thanks guys!