Hi, I just joined this forum. I've been looking at it for a while, but the main reason I joined is because I'm having the exact same problems as CircaAtomicAge.
I got my hot rod deville last christmas, and it's my first tube amp. I don't know much about them, so I have no idea why the rattle happens either. Mine also happens at certain bassy tones, like F#.
I also think one of my power tubes is dead, but i conveniently noticed after the warranty had gone out on them
. One of them doesn't light up or get warm.