On the side-note of color tubes with burn, you don't _normally_ see modern color computer monitors with burn, until you start working with junked equipment from state offices, hospitals, etc. Server consoles are pretty bad too - I've seen monitors that very clearly show "Windows NT Server" or "Windows 2000 Server", burned sharply into the screen. Once I even saw one with Windows 2000 burn _and_ NT Server burn. They must have upgraded
. Or offices that have their company logo as the desktop wallpaper, those typically get etched into the screen pretty good. You also see login screens burned into the tube quite a lot. Occasionally, you can see the whole desktop, complete with icons and readable text - even the icon headings of "Microsoft Word" are readable. And that little MS word 'toolbar' thing.
Arcade machines, especially the old ones, get burn in attract mode, or just from use. You can always tell a monitor from a Pac-Man or Ms. Pac-Man machine, the maze is clear as day. One time I even saw a TV set in a thrift store with Atari 2600 Pac-Man burn in it.
I guess that under _normal_ use, the phosphors in a TV shouldn't degrade too much, so rebuilding the tube would be only a replacement gun. It seemed like I read somewhere that the really old B&W tubes suffered worse phosphor degredation - until they switched to an aluminized screen or something like that. But the tube rebuilders probably would look very closely at the duds as they came in, and only rebuild the ones that were going to work well when rebuilt. But I am really curious, if they did replace phosphors in the tube at some point - how did they do it? I can just see someone trying to scrub the old phosphor off the tube with a long brush or something, like cleaning out a bottle.
-Ian