Admiral 14UY3C Chassis CRT Question

[Chris K]

I'm trying to coordinate a purchase with the ETM of a new 14RP4. In the meantime, I've been doing some work on the original tube. This is the one I mentioned a while back with the loose end cap. I de-soldered and re-soldered the CRT leads and put my Super Mack Sencore on it and it still showed it to be deader than dead. I let it sit for about half an hour at 6.3v and it did not improve noticeably so I bumped the voltage up to 8 volts for a little bit. Bang! Emissions suddenly went up significantly into the good area. I brought it back down to 6.3 and it held good emissions down to 4 volts. I think something is funky. No shorts but there's still no cutoff and the tube gets warm, warmer that any 6.3v CRT I have tested on the glass around the filament. I'll test it in the TV as soon as I've done some chassis work but any ideas what might be going on with it? Thanks!