I'm sure the linked threads will mention some of this too. Go to Wallyworld or Lowes and get a nice thick rubber mat for the floor. Your bench should be clear and wood or plastic, I like masonite surface myself... not metal. Mount the power source (like a power strip with on/off sw) Have a fair to good meter available.
I like a swivel chair with rubber caps on bottom, I'm insulated well from the floor. That is a good start. ANY liquids are not to be on this bench top (Exception: Small spray Can of 226 contact cleaner with lubricant from Home Depot). Set your drink away behind you on the desk etc... no liquids. So now you can get shocked but it much more difficult for electricity to ground to the floor itself thru you:)
I have pencil diameter lucite rods about a foot long I accumated somewhere which I use for probing and shoving things around a bit. Solid non conducting plastic with no metal shank, not screwdrivers. Nippers pliars etc all have rubber insulation.
I use large blocks of wood to support the amp, they are cut to fit nicely around the transformers. Just a yoke kind of thing so it cannot slip fall or slide. However you do it, you need to be able to set the amp securely face up or more likely face down so you can see the guts. Get a good light so you can see what is there clearly.
I like to ground the caps with rubber shielded alligator clip leads. One goes on the chassis the other right onto the large leads of the cap. Bleeding down is not a 2 second proposition the caps will actually glean extra electrons from the circuit and recharge up some... give it time, and drain each set of the larger caps.
Now, unplugged and alligator clipped caps bled off, using your layout diagram eyeball the thing looking for a power section, a pre amp section, and an output section. Try to reference back to the schematic till it makes some sense. Read up on these till you get a pretty good handle on it. The 6V A.C. thru the light bulb to the tube sockets which powers up the tube filaments is there also.
When you are ready, pm Wally and let him help you find those 6V a.c. filament heater wires. And off you go EZ as that. Eventually you will read the B+ DC volts several places and there will be some clarity for you.
I doubt your transformer is bad, components in circuit read differently often.... could be but I think with a little troubleshooting you will find a broken wire, dirty pot, cold solder joint etc. It has had life before, it will again.
ps: Lubbock huh? I'm originally Big Bend coiuntry around Marfa. Glad to meet ya' boy howdy.
If all else fails... buy more tools