I have a Tivo HD on Atlanta area Comcast cable. It has one Motorola-M, Dual tuner, CableCard installed for the past two years w/o any problems. Starting a month ago one channel 806 , NBC part of the HD basic service started getting checkerboard and no signal message about 90% of the time, works on and off 10% of time.. Fails only one channel on tuner 0 or 1 within the card. Pulled the card and reseated it a couple of times, powered off the Tivo, symptoms are still the same. Is there anything I can do prior to last resort of calling Comcast, is it a bad CableCard or a week signal just showing on one channel. Is there anything I can check.. Help would be appreciated !!