DIYbanter - Sanyo CE28WP4 - B with yellow picture

I posted a couple of weeks ago about my Sanyo CE28WP4 - B widescreen
set going wrong wehn my stepson ripped a scart lead from the back.
Basically the picture became very washed out and took on a blueish tint
whihc was most notable on any dark scenes the set displayed.

I'd had a look inside for anything that I could see that may be
obviously wrong but couldn't really see anything. I did clear a lot of
the dust out but the first time round that seemed to make the problem
worse. After taking the back off the set again I had a prod and a poke
around and the set went back to having the blue tint, it was a crap
picture but was just about watchable.

I decided to have another go at trying to find anything wrong yesterday
but failed again although this time I was able to make the picture much
better by adjusting the pot on the flyback for the screen brightness,
and playing around with the brightness/colour/contrast controls on the
remote. All was well for around 2 hours then the picture stuttered for
a second and came back on a yellowish green. Other colours are still
displayed but with the yellowish green tint.

Does anyone know the likely problem and more importantly a soloution.
I bought the set second hand only a couple of months ago and although I
didn't pay much for it I was hoping it would last a bit longer than
this.

Any help much appreciated.