Weak CRT or not?

[Electronic M]

Probably HV protection. My CTC4 shorts the HV if the back is removed. The 21CT55 would short the HV if the cage was opened...

That 1M resistor should be shorted or replaced to prove its innocence.... Those old carbon comp resistors can do strange things at HV. For instance the carbon resistive element can go open but arc over at the open can make a faux 1M resistance that a meter sees yet it can't support normal HV current. May not be the case but better to rule out than have hanging...