Ampeg vl-502 tube socket short?/fire

[davis1866]

this amp 50 watts tubed, el34's or 6550's (currently el34's) when fired the channel 2 tube socket FIRES and breaks off the plastic peg in the middle of the tube contacts, it shoots a little fire out between pins 3 and 4- i think?

there was an issue with the R16 connecting to the hum balance and the light board but I've removed the resistor and the light board, the fire occurs with or without it and doesn't reach the resistor.
I turn it off immediately and none of the fuses blow, the 10A internal, 4A and 2A (which has a 1A in it and always has) outside of the amp

is this a ground issue? the previous owner covered the bottom of the amp with tin foil and took out some of the grounding screws that connected to the power tubes and the clamps that keep them pinned down. He put a thin metal ring under one of the ground screws that connects to the R16

and he blew the hum balance too, I don't think it works, it's melted and it never really changes the hum the amp makes- which normally isn't an issue.
during one gig the amp cut out, blew the R16, first pre-amp tube and the main Fuse(4A) and the internal one (10A) i've not been able to fix it since, I've been blowing resistors to replace R16

attached is the schematic for the 1002 which is the 100 watt version with 4 power tubes

[52 Bill]

when fired the channel 2 tube socket FIRES and breaks off the plastic peg in the middle of the tube contacts, it shoots a little fire out between pins 3 and 4- i think?

It sounds like the tube and the tube socket have been damaged (arced, carbonized) and will need to be replaced. I can't believe that the fuse hasn't blown.