Paul,
I am ordering a couple of different brand 6080 tube and a couple of different brand 12AU7 tubes from Tube Depot (Digikey).
I repeated the resistance checks and it all checks out. Because the flash/puff I experienced came from the side with the rectifier diodes, I have removed all four of them from the circuit. They all measure between .501 and .504 Volts. Is this the value that you would expect? If so, I’ll put them back in the circuit.. If not, let me know and I’ll order new ones.
Thanks,
John