docz wrote:Ok, I paralelled two 270R on both of the 6.3V lugs of the transformer, then I hooked those up to a cable and connected that to the screw where the ground wire from the mains is connected.
Great work, forbidden practice.
Great that you constructed the center tap. Very bad that you joined it to the mains ground. You must move it. Move it anywhere else but there, preferably to it's own spot on the chassis. As I suggested a transformer bolt is OK. One of the ground lugs on a terminal strip is OK, as long as nothing else is there.
The reason you don't want to use the mains ground is that you now have a potential connection between the mains supply and the filament winding. One function of a transformer is to fully isolate the mains supply from the amp's power supply. You've potentially defeated that if something should go wrong. Fix this NOW, please.
I now have a steady 6.0V supply to the filaments, it used to be between 6.3 and 6.8. Result no more loud hum, unless I put my guitar into the amp, or I touch the end of the coupling cap on V1 and V2. It does still hum, but very very low. The noise however is still there.
Yes, I was reasonably certain the artificial CT would quiet the hum, which you reported earlier is 50Hz. 6.0V is fully acceptable. You'll find that it varies with the mains line voltage. Use your meter to check your mains supply at the wall socket once every hour...you might be surprised at the variation you see.
It is likely the filament wiring is not your only source of hum. The question is whether you can live with it or if you want to continue the hunt.
The guitar and cable are a big antenna. You'll get hum from your pickups. Mute with your hands or turn volume down at the guitar. If that makes it go away, it is normal and not the amp.
Just a quick question, the PT says 6.3V 2A, does that mean I should use 12W resistors instead of the 1/2W I'm using now for the artificial center tap? Or is that how much current that is available, and not how much is actually going through it? This is still something that confuses me a bit.
I think Martin covered this very nicely. 0.5W is good for most everything in guitar amps. The power supply laddeer would be one exception. Cathode resistor on yoru power tube would be another.
I did some "chopsticking"
Getting to be a real pro!
no effect, but when I accidentally hit the coupling cap (0.02) on V2 it made it worse, so I tried doing some more random poking, and I found that pushing on that whole terminal strip where that cap connects ( this is the one that V2 to EL84. I also measured between 3 and 5V DC comming out of that 0.022 cap, does that mean it is leaky? All other caps were ok. 0V DC
Yes, that is the art of chopsticking. Tap resistors and caps, move wires, whatever. I think you found a bad one. There is nothing wrong with trying an inexpensive film cap. In the bad old days, manufacturers were known to be penny pinchers and they made many of the amps we know and love. As for the cap, if you find .02 or even .025, don't be concerned about the exact value.
Chopstiking 
I'd swap that cap and see if that would help.