"When they rebuild CRTs, how do they let the air in and avoid damaging the screen?"
I am not sure, but I think I know from a dud gun color gun assembly that Scotty at Hawkeye sent to me.
The old color gun assembly was still attached to the bakelite socket and about 2 inches of the glass neck at the socket end of the neck. The glass neck assembly was severed from the rest of the neck in a very clean fashion. I examined the glass of the neck assembly closely to see how Scotty accomplished this feat. It appears Scotty scored a line with perhaps a dremmel tool where he wanted the neck to crack off. I assume he then tapped on the neck where it was scored and the glass tube made a clean break around the entire circumference of the glass neck. I am guessing prior to tapping on the neck to make it crack off, that Scotty might take some scotch tape and tape along the spot where the crack is going to take place. Taping along the point where the crack happens, would seal the air from inrushing to rapidly.
Like I said, all of this is just a guess from what I could deduce from the dead gun assembly Scotty sent to me.
Maybe someday someone will do a video of Scotty performing his craft so we can all see how this rebuilding is done.
