1 JimmyR 1 month ago A while back I mentioned in a thread here that I had a friend's Blonde Bandmaster here, trying to figure out why it sounded like poo. Well I got it working. All the resistors measured ok, voltages were to spec - turns out the caps in the PI were leaky. So once I replaced them and a tonestack cap with lovely new Sozo blues the amp came back to life. The overdriven tones are ok but not amazing, but the overall sound of the amp is great. It really does have elements of BF and tweed in there. And the harmonic tremolo is interesting!But I got a text from the owner yesterday. He says that after about 5-10 minutes of playing with the volume at around 6 the amp volume just dies. You can still hear it, but it is a lot lower. No crackle, no fuss, just all of a sudden the volume drops.Let the amp cool down, start it up, same thing. Loud for 5-10 minutes then sudden volume drop.Obviously something is warming up then failing. Has anyone had symptoms like this before? Any clues? My friend has tried replacing all the tubes with known good tubes but no difference. All the electrolytics look recent - I didn't have to replace the originals, it had already been done. I don't have the amp in front of me right now.Suggestions?