Screen goes RED on Samsung TV

[RODALCO]

Type : Samsung CS-7277 PF.
29 inch CRT TV 1996.

This TV has the occasional intermittand fault that the screen goes red.
Turn it of for 10 minutes it may be ok for the next 10 or 20 min, or screen goes Red immidiately.
Next day it is OK and similar symptoms happen after about 1 hour.

I did put a fan behind the TV but problems reappear, but not as often, it seems that temperature may cause the problem.
Also not sure if it is an internal fault in the tube with the Red gun shorting out or so.

Can't see anything obvious burnt or cracked or poor soldering in the back.
All elco's look ok too, and are not bulged.

Any tips from someone experienced in Samsungs would be greatly appreciated.

[minnie]

I'd take the back off the set and turn it on and if the picture was normal, I'd tap on the crt board with the plastic handle of my screw driver. I'd say there's a good chance you have some cold solder joints on the crt board.