[Nick3092]

If there was an issue with overloading, wouldn't I hear some distortion on the lowest bass setting as well? Not arguing, just curious. As a clarification as well, the distortion is mainly when the bass-y parts of the songs play. So it's not distorting the entire signal. I do have a signal tracer. I guess I could put that on the plate of the 41 and see if it experiences it as well to clear the speaker itself.

All of the tubes (except rectifier and OP) tested weak originally. As I had to get some new tubes, I ordered these as well. Plus since I have a 39-6 which also uses the 75/78 and a 38-10 that uses the 6A8, they would be good spares to have on hand. Right now all the NOS tubes are in. As I recall (my notes are at home right now), my Hickok 533A said the diodes were good on the original 75. But my Weston 981-1 (which somehow tested the diodes together, as opposed to the 533 that tested them individually) showed them as being weak/bad.

I guess I can try swapping in the originals 1 by 1 tonight to see if that makes a difference. I can also try the ones from my 39-6 and 38-10 to see if they change anything before moving on to detuning sections.