Tube tester for a Predicta 21EAP4

[rickfray]

Thanks, I'll have to find out where to turn in my EE degrees for not thinking about that. I disconnected the other end so I could remove the chassis. The only markings on the tube is a label that says 21EAP4. Is it still inconclusive whether it's 2.34 or 6 volts until I do the current test?