I finally resolved this problem this afternoon and tonight. I'm still not sure what was the cause, but at least I have my channels back.
I tried using an inline satellite amp. No improvement. (100 ft. cable run). Then I ran new RG-6 cable. Still no improvement. I took a TV and receiver out to the dish and tried to peak the signal. I was still getting a lot of pixelization and audio chirps. The 11800 transponder has had the most problems for me. I managed to bring up the quality reading by about 4%, but still had problems. Then I found if I nudged the dish a little to the west my quality would drop a little, but the picture became steady. I still think that interference was a factor.
The end result was (quality readings)
12104 went from 58 to 54
12114 went from 72 to 62
11720 went from 42 to 52
11800 went from 63 to 56
10235 went from 63 to 57
These readings were all taken during clear, cloudless days. I'm not sure why they didn't all go up or down consistently. Even though I have generally lower quality, I'm not having any problems with reception. I did try moving the dish back for the higher readings, but the pixelization, chirping freezing would start up again. Perhaps my primestar dish is warped just enough that I'm getting intereference from the DishNetwork satellites unless I aim slightly to the west. I'm guessing.