Mesa Boogie F-30 Humming like nobody's business

This hum is overpowering. Following suggestions, I pulled V1 (12ax7a) and the hum disappeared. I treid swapping in other 12ax7s I had and which don't introduce hum used in V2 socket, but the hum persists.

I have a schematic, but it's larger than the 300k limit to post here. I can read schematics, albeit slowly, have a good head for debugging, and have a multimeter and scope.

The amp is on a pc board, but by tracing from the tube sockets I should be able to follow a signal along.

I believe I have ruled out a bad V1 tube. I don't know where to look next. Any suggestions? I've got sense enough to work safely in the chassis and I really believe I can learn something valuable by shooting this bug. All help greatly appreciated.

does it have the input jack ground touching the chasis or is it grounded through a Star ground way?

look for a busted ground in the input jack area
or maybe the jack itself

or maybe a broken ground on the vol control,
 
just ohm out all the ground connections in the input block, which includes the jack, V1, and all points inbetween.

remember V1 is actually two tubes, so there are parts between the two tube sections to check also.

is the volume turned up or does it happen just sitting thjere,
volume on zero, no guitar plugged in?

Thank, rich and CJ. I'll be back over there on Monday. I'll post answers to these q's on monday eve.

Damn, it fixed itself! I hate when that happens.

The input jack was grounded, the hum followed the input gain pot, in both channels.

I started checking grounds and somewhere along the way I must have probed a cold joint (I'm guessing). The hum has all but disappeared, it's only audible when the input and masters are full up, and at normal playing volumes are well below the signal, just barely audible.

If it starts up again, I'll pull the PCB and reflow all the connections to ground, but for now, I'm going the lazy man's route. I don't play out anywhere, so the amp is not "mission critical"

if it is a pc board, you might have a broken trace,
those boards can sometimes resonate with the music, certain notes,
like an ultra sonic bonder, when you hit a jimi high C,
do you usually crank the sh*t out of it with exterior fuzz?

try a heat gun on the chassis,
or a light tap with a plastic hammer, in specific areas, don't just wack the whole chassis with a baseball bat,
we will save that for later.  ;D