Take the cable off and look at the connector. If there is a copper wire in the center that doesn't come quite to the edge of the connector, it means the cable isn't going on tight enough. (That wire has ti insert itself into the connecter on the back of the TV.) It could be too short, it could be bent over (you can straighten that out with a pair of tweezers, but that sounds like the problem to me,,,a bad connection somewhere in the able connection.