Funny how you start to hear your amps better over time. I've come to realize my VibroChamp has a low, constant sizzle *as soon as you turn it on* (it sounds like it's in the switch, it starts so fast). I know this is probably suggestive of a known issue. Which issue: where to look, how to fix? FWIW the pots are original. I replaced the cap can and other e-caps. I kept the single-strand heater wiring. Just because the slide switch felt so 'loose' I did replace it with an NOS, but of course the noise didn't change. Suspects? I'm running all carbon comp resistors except for the 6V6 cathode. This includes the dropping resistors (2w) and V1 plate load resistors (1w). Most are NOS Allan-Bradleys, one is some other brand, and only a couple were original to the amp (they tested good though.) The amp works and sounds great otherwise. And let me repeat: The sizzle starts the second you switch on. That's gotta be a clue, right?