Update on my problem: I'm running analog cable only (no cable-cards and I disconnected the OTA input for now). Tuner 0 was not able to get channels 43-53 all of yesterday (tuner 1 was fine with them). Last night, tuner 0 suddenly stopped getting 25-41 as well. That's a much more serious problem for me: it includes most of the networks! This morning I noticed in addition to not getting 25-42,43-53, tuner 0 was having problems with channel 16. It would get 16 for a split second every 2-15 seconds or so, quite randomly. The quality was excellent for that split second. The rest of the time the picture was a grey screen, with the "searching for signal" message popping up if it was a big gap between signal. Tuner 1 has no problems with channel 16. Since a marginal situation like this is an excellent opportunity for debugging, I spent some time trying things. Basically I got no differences in behavior for anything I tried: rebooting, turning off for a while, disconnecting the OTA antenna. Perhaps most importantly, I got no differences when I inserted a 6db attenuator on the cable input. The marginal situation of channel 16 didn't change, the channels tuner 0 and tuner 1 got didn't change. To my mind, that just about eliminates signal strength as the cause of the problem. The fact that tuner 1 had no problems after attenutation means my basic signal is strong enough. If I'm correctly interpreting channel 16 as a marginal signal for tuner 0, then a 6db difference in strength should have some effect if the root cause is signal strength! I'll call up TiVo later today and see if they want engineering to run any tests on it in situ. Otherwise, I'll just have to exchange it.