Zenith 7h822-z tubes not lit

[Tennangler]

I looked up the pinout after I wrote. Should have done that first. I checked continuity across pins 3 and 4 and it was open. A friend with a tube tester tested it as bad. He told me a 35c3 he has will be a replacement. I was reluctant to use it but tried it anyway. The radio came on but has a hum. The hum does not vary with the volume control.
First, is it ok to use the 35c5? Second, if it is does the hum indicate a grounding issue?