alba tvd 3408 portable tv with dvd player?

this tv combo worked great but now it has developed a dark picture after about 10 minutes when i switch off it comes back on ok with good brightness but the colours are wrong it all
looks like the green gun is missing ie the pic is very blue - does anyone know what bush chassic is the same as this alba model as i was thinking of going to my local second hand shop where they sell all types of portables and maybe i could find a good chassic that will accomadate a cd player as well--thanks for any help--nedw