I just bought a vintage 1965 Deluxe Reverb. Unfortunately, both channels sound buzzy/fuzzy/fizzy especially low frequencies. Even at low volumes (as low as 2 on the dial). I tried changing power tubes, rectifier tube, and speaker. I also changed out the 12AX7s (I don't have spare AT7s). Still the same issue. I made sure the baffle is tight as well. What sort of component failure causes this? Should I just check voltages inside the amp as cited on the schematic (I know how to do it safely). If you need sound clips, I can try to make some.