TV Color issues

[MBombchu]

Hi guys, so i inherited a nice 25" crt from my grampa some years ago. So far it has been working great, beautiful rgb, picks up any rf signal, and is just plain great. However there is a color glitch getting more and more common. One color is sometimes missing. However this only occurs when using composite, never when using rgb. This can be fixed by first turning on a rgb source and then switching to composite, but i have to repeat it all 15 minutes or so.
What could the reason be ? I guess not the cathodes as it works in rgb mode !?!


Please help !

Thx

[number47]

Some cold solder joint or leaky cap.

[MBombchu]

But wouldnt i also have problems with rgb then ?