I traded for a tweed Bassman 4x10 clone not long ago. In the last while I've posted several threads here related to it on one topic or another. I love the sound of this amp, and I'm enjoying the process of learning more about tube amp function by studying this amp in greater detail, but I am up against a nagging problem. I could just take it to a tech, and will if I can't solve it, but I'd like to continue trying for the time being. Here's the problem. The amp sounds stellar, with extremely sensitive touch and super clean chime, but it has a sympathetic buzz of some kind on low F# or G notes played on the 5th or 6th strings. It sounds like a mechanical buzz that comes through the speakers and might be coming from a tube with loose internal components, but I've switched out all the tubes, and it's still there. If I never had to play low F# or G notes, I'd swear it was the best amp ever, but I'm going to need all 12 notes moving forward. Any thoughts?