A couple of weeks ago I noticed that one of my cable channel was not getting any signals. I checked my Comcast lineup and found the channel should work. So I thought I should contact comcast but was too busy to actually do it, and I was not in a hurry because I don't normally watch the channel. Yesterday another channel, which had been working, stopped working while I tried to record a show. It suddenly clicked in my head that I should check my cable connections, so I traced the cables and, voila, found a couple of places where the connections were loose. I hand-tightened them and the channels came back!