Cathode flare?, was this green glow more of a flash on start up? , some flare right up one leg of the tube, I’ve had one of mine take a fuse out like that!
It was ALL of the Inside Tube, He had been sat Un-Lit for a While...
WISH I had got a Photo But I was Fascinated By it and just sat there Watching it, Might Go and Turn Him on and See
IF it Happens Again....