Its an old 210. Just got it and fired it up. Im getting some crackling/static noise. This is remedy when I hold the 6V6 still with a towel of course. Hmmm, microphonic tube, fair enough. Its an old KEN RAD. So I swapped out the KEN RAD for an old RCA that I have in my tweed champ clone. This caused the amp to sound really quite and obvious crappy fizzy, static distortion. When I sawp tubes in my Champ I never get this. I figured cause its single-ended etc. that a tube swap was ok without rebiasing. Any idea what this could be. The old RCA is a NOS metal one from the 50s or so.Like I said , it works fine in my champ. Anyone have any tips how to remedy this? Amp sounds fantastic other than the static. The vibrato is all that people say it is. Very trippy and horror movie like This sucks cause I know its something very small but damn I just want to crank the amp and see what its got.