When to use heater center tap

[Chuck H]

Just thinking out loud now, BUT...

It seems I've read a lot of posts here over the years where a power tube failure took out the humdinger pot on an amp. Any chance it's still, at least, not an unreasonable idea to rate false filament CT resistors to act as fuses.?.

[trobbins]

Anode to heater faults from pin 2-3 flashover are best managed by suppressing excessive anode voltage excursions, and keeping the valve base clean between pins 2-3. I've seen amps with insulation sleeved anode pins - an appropriate solution for that vintage time, but modern MOVs make for far better over-voltage protection across OT primary half-windings nowadays.

As Enzo identifies, short circuiting anode to cathode circuits through the valve's heater is not uncommon when the valve base locating spigot/peg has been broken off.