Model UN55FH6003F, have a picture that comes and goes (sometime have to hit it on the side), The picture appears to be very very dark went it goes can almost make out the picture on the screen. I always have clear sound. Looked at the three boards, only mark I can find appears to be a small black smug mark on the back of the power supply board. All other boards look good. What do u think????

Televison & Video - Samsung