I've generally read that 7JP4s can't and were not ever rebuilt. Perhaps because of the gun and deflection plate complexity or the type of glass used.
It's been discussed here before.
http://www.videokarma.org/showthread.php?t=264395
Well my gassy 7JP4 with the ion burn sure does appear to have been rebuilt. There is a very noticeable weld seam on the neck.
It also does not appear to have much of a getter. Either that or it's been consumed so completely there's not even a white film left.
