Problem: While playing recently, my DT-25 suddenly dropped volume significantly and had a slight burning smell. I figured it was a tube(s) going out, so I bought some new ones and replaced them, but when I went to bias them, they were super low! Instead of the 25 (+/-3), they were around 7-8. I turned the bias, but then the weirdest thing happened - any turn up would start an unstoppable climb to 40-50, then it would suddenly kick down to 14 or less. It would stay that way until I turned the bias up again, and then the same thing every time.
I checked the fuse, but it seems intact. Since power was going to the tubes, I figure it can't be that anyway.
I may be wrong, but I suspected it may be kicking into Low-Volume mode as a safety feature.
Any idea what's going on? How do I fix this?