I have an unmarked 16" metal bell CRT with a "Z" painted on it. I'm pretty sure it's a 16GP4 just going by the dimensions.
I tested it with my Sencore CR70 and have absolutely 0 emissions. I suspect there's either an internal break in the cathode or it's completely worn out.
I then tried every trick I know of:
Touched up the base pins with a soldering iron - no effect
Pulled off the base to look for a break inside - nope
Rejuvination - no effect
Auto-restore - no effect
Even tried to reweld the cathode from every angle with no luck.
Anyone have anymore ideas ?