There should be 3 dots in my comment that will allow you to send one Bobsyouruncle.
I have a 6400 - Model# UN46D6400UFXZA
Screen overheats on the top left corner (burning hot) and horizontal lines on the top originating from the over heating spot all along the screen. About 2" starting at the top on the screen all along. Tried letting it cool down and resetting the TV. Problem still persists.