I was having random channel tuning issues with a Series 3 HD unit (model #TCD652160) in a basement bedroom. I tried another identical Series 3 unit in this room and had the same problem. I called Comcast to have the cable card repaired (both units), but still had the issues. Since they are older Series 3s, I thought it was the TiVos themselves and even at one point thought it was the cable card firmware.
I saw some post here about cable card firmware and how getting the firmware updated fixed the problem, but these were issues mainly in FL & I am in GA. I called and tried to get Comcast to "upgrade" the firmware, but they told me this was not available for me & their engineers said it wasn't the problem.
Recently, I got a discounted 2-tuner Premiere and stuck it in this bedroom instead thinking these random tuning issues would go away. Nope and still had them. Another thing too is the old Series 3 TiVos were moved to the basement rec room and work fine on another outlet so it made me then think there is an issue with that room and its outlet.
The only thing I can think of is there is a Comcast installed amplifier in this room that is needed for the entire house and our Comcast internet. Its the only factor that is different from the other 4 perfectly working TiVos (Series 3 and 4s). Here is a picture of the Comcast installed amplifier.
As you can see from the pics, one coax end goes to the TiVo Premiere in that room. The other end of the splitter then essentially goes back outside to the Comcast coax distributor for the other TiVos (and is amplified this way)
Does this sound like its probably the issue? If so, I have to figure out where Comcast can maybe install this AND not affect other TiVos in my house (currently 3 other live TiVo outlets)