I just bought a Boogie Buster head NOS today for real cheap, but it doesn't sound right. It doesn't get very loud, is lacking in low end and punch, and distorts very easily. When it is distorting, it has got a buzzy sort of distortion, rather than the round grind it should when turned all the way up. The place I bought it from said that it had been in the shop with a transformer problem, and claimed it had been fixed. I've replaced all the tubes. Does this sound like an output transformer problem? Any guesses as to what may be wrong?