Samsung LE40R73BD Television?

I have a samsung 40" lcd tv which has a red line, sometimes yellow, running down the screen, it's not always there, but when it is I move the tv a round a little and if it's red line it changes to a yellow line or returns to normal, how can I mend this problem. I know my way round a pcb and can use a soldering iron! All I need is to be pointed in the right direction. Many thank.