You should be able to check the heater filament.
I thought there might have been a specific ohm range between pins.sensors I test at work have them I have to call manufacture for specifics. Like an igniter for heater 50 to 75 ohm is good range,will work above 75 ohm but ready to pop.
There are none to call!...I have to call manufacture for specifics
So to properly test a tube requires a tube tester ,not a multimeter
Sure a lot of trollin goin on
Where did all this machinery go?