crt red gun

[bgk283]

hey guys, i picked up another combo like mine the other day. it has raster, cleaned the contacts on the neck of the tube and the socket but am getting intermittent red gun activity, any suggestions on what to do? when i first turn it on the red will work but putts out after a few minutes. its a 21fjp22 original tube in the set thats been sitting in a basement for 27 years. i guess this is how all the projects get started. thanks Bruce