Tosh rear pro Yellow peril

[sipian]

Just got my second 42PW33 set in just over 6 weeks. The first went back because the RGB input on SCART one wasn't working properly.
Now this one seems to have a mind of it's own.
Thought I had a really good picture and was happy with it. Now there is a Yellow shadow/stain evident in the bottom left corner of the sreen (it's a black shadow when on blue screen.) It seems to be there then not, then really evident then not.
Also no matter what I do with the picture settings there is a lot of 'tizzing' of colours. Mainly on Sky it has to be said, but also on the component feed from my DVD player.
Any suggestions please ? I'm loathed to box it back up again and I'm not sure they'd take it anyway. I know I've seen a good picture on this set so I want to get that back.

Help please !!

[KISSMAN]

I Had The Same Prob But A Red Stain Not Yellow And A Few People Have Had The Same Prob,even The Shop One Had 2 On It,cut Your Losses And Get A Refund