You can have good signal and still get pixelation if the lnb is on the skids. Swapping it out would be a good start.
AND it may very well be. It's from the early days of two dish installs. But I have had Duals up there and think I have a new one still in the box. I'll have to go see if I can dig it out. OR a single from Walmart can't cost all that much. Couldn't find a Single DPP. But a triple DPH is only $33.