For the past few months I've been having a couple channels that show 'No signal' on my S3 HD (Tcd652160). I have Comcast and use a single M-card. The problem is with two of the local channels. I also have a Premiere and a Premeire 4 in the house and neither of the S4 have issues with those (or any) channels. All of the cable feeds receive approximately the same strength (coming from a 4-way splitter). Since my S3 HD is in a less used location, I haven't been all that active about fixing it, but yesterday, I finally decided to do some testing. I had already tried a different cable card and that did not make any difference. Yesterday, I took the S3 and hooked it up in a location where I already have an S4. The S4 typically sees 60-70 signals in this location. The S3 hooked up saw no signal on any channels. I removed a splitter (for a MOCA bridge) at that location and I was able to see some signals with the S3, but there were quite a few channels that saw nothing. The S4 works with the splitter, the S3 is marginal without the splitter. My question is has anybody else compared the cable card tuner in the S3 HD to the S4? If so, do you find they are equally sensitive or does the S3 suffer from lower sensitivity? I suspect there is an issue with my S3 tuner (perhaps from a lightning surge or something) and I was going to try a replacement from Ebay, but if others have found the S3 tuner to be generally weak, then I will probably just go ahead and get a Tivo mini to replace it. I don't want to give up on the S3 because it has lifetime service.