Put the CRT on the tester, mostly dead at first though the cutoff showed signs of life, kicked it up to 9 volts for 30 seconds or so and the emissions came up very good, dropped it back to 6.3 and it dropped off but still in the good range. Cooked it again at 8 volts for another 30 seconds and now it stays in the good range and the cutoff is excellent!
After letting it sit on 6.3 while I took pictures and typed this up and it's checking high in the good range! Not perfect but not bad for a freebie.
Take a look at the CRT face, that's not a shadow, that's how the phosphor was applied to this tube. I can't find much on a 12TP4, anyone else have one and is it done the same way?
I'm really torn on this one, I'd like to restore it because I'm sure it's much rarer than anything else I have that could use this CRT, but with the missing doors I think it's pretty much a lost cause, at least if I want it original.