12-19-2013, 11:47 AM
I'm with PAradiogeek. I'm very new to old radios, but not to tubes in general. I've seen many guitar amps tubes glow blue/violet that were perfectly fine. Perhaps that's not the case with these older tubes, and I'd love to learn if I am wrong. If the tube checks out OK and there aren't excessive grid currents, I think you are good to go.