Has the PR Mux turned down the power? I haven't been on this bird for a while and it seems much lower from what I remember. All other TP's are fine. Tried tweaking the dish but no dice.
My suspicion is that some programmers do maintenance of some kind on the weekends that can cause the signal strength or quality to degrade. I saw the PR Mux breaking up yesterday, but today it's fine again. There's a few channels that I can just about guarantee will be barely watchable on Saturday morning, but they are generally fine the rest of the week.