tint stain on the screen,help

[silv]

Hi guys; i have here a RCA ctc187 that i found out on the side of the street and the only thing i found that was wrong was the RT1401 that has fallen off so i replaced it with a RT from a ctc203 chassi that i had hanging around,so the Tv fired on and everything is ok exept there is a tint stain on the screen when i turn it on and i use a degauser to take it off but later it comes back or when i turn it back on,is there anything that i can do that can make this tint stain to go away for good? thanks in advance.