On my 510, even though I had good signal strength on all the TPs that relate to
Dallas SD LIL major networks (NBC CBS, ABC, FOX, PBS), and on ESPN, etc, I was missing all of those channels. Problem persisted, even though Check Switch showed 110/119/129 were all normal (Good).
Dealer came and we replaced the F connector on the 510 coax (coax is pretty new and only 25 feet long). No change. But when he replaced the DPP Twin (Dish 1000) the problems went away. Did not re-aim the dish, since signals were high 80s, 90s-100s.
There was a spot on the back of the old DPP TWIN that was hot to the touch and dealer said this temp level was abnormal.
The other side of the DPP Twin was running the 622 via a separator and was fine on all channels! One has to conclude that one of the Twins had a fever but not the other. Strangely, I swapped the coax from the 622 to the 510 and the 510 problems persisted after a Check Switch. Maybe the 622 side of the DPP Twin was intermittent and some of the incomplete recordings and recording lockups during playback on the 622 were also caused by a failing LNB.
In N. Texas, the DPP Twin was out there in the 108 degree weather last summer and lately in the general area of some vy strong lightning. This may have accumulated to "fry" the DDP Twin.
One clue I had was that I was getting the 44-hour EPG (119/19). But the 9-day EPG (119/18) would not download. Also I was missing WGN on 119/18 and other 119/18 channels. Others that had signal but no picture, were 119/4 /6/ /8 and 110/20 Dallas LIL major SD networks - among others. When WGN on 119/18 came back after the LNB swap, so did the 9-day EPG (119/18). And so forth.