How to tell if a CRT is rebuilt?

[mstaton]

Yes, that is a rebuilt tube. That ripple area is where the cut and re-mounted the new gun assembly. That generic label gives it away. That paint writing on the CRT is not from the factory. You will notice one that looks burnt and the other newer. Looks like after the original labels were removed, they kept track of the model by writing on it but obviously it got burnt so they wrote it back on after it was removed from the furnace and before they slapped a new label on. Most rebuilds say "This tube employs a used glass envelope"