This might be a bad solder connection in the circuitry that drives the red gun. Look at the little cicuit board that is stuck to the picture tube scocket and look on it for bad solder connections.
PS: You need very good light and a magnifying glass or better yet a pair of close-up (reading) glasses. I use +2.75, the stronger the better. And use silver, not lead, electronics solder and a solder pen not a gun. Unplug the set before you start.
Tnis can also solve the same fault in computer CRT type monitor.
dcrandall222@netzero.net, October 2005