With due care and Multimeter set for high voltage AC, with tubes removed, check for high voltage AC at pin 4 of rectifier tube socket.
If you have high voltage AC on pin 4, you should have high voltage DC on pin 2 and 8 when rectfier tube is installed. (Change meter to DC High Voltage setting). If you have high voltage AC on pin 4 (and 6) your PT is good.
If waht you say is accurate, your description foretells a bad rectifier tube.
5F1 Champ & 5E3 Tweed Kits, 5F6A Kits. See Vendor Forum Specials & www.BootHillAmps.com