Recently my lower cable channels (60 and below) began to look like on older TV that has poor antenna reception, ie. they all have lots of low signal snow and they flicker. The upper HD channels are clear, but have low signal artifacts every few seconds. This started all at once, out of the blue. I have moved the TV to different rooms and different coaxial cables around the house, and same result. ALL four other flat screen TV's around the house are clear. I don't use cable boxes on any of the TV's. Could this be a bad coaxial connector on the TV? The connector is not loose or anything, but the TV is about 7 years old. All HDMI inputs have a clear picture.