HV rectifier tubes rarely glow or just have a slight glow. It
dont take much heat to get the electron to make the jump
at HV. Best quick test is:
Unplug the top cap & let it hang away from metal.
Take a GOOD well insulated screwdriver & get it near the metal
of the cap. You should get a healthy apx 1/2 inch arc.
If not its the horz osc, output or damper IF its a tube.
73 Zeno
LFOD !