Weak Transponders?

For the last week or so, I have had poor reception on a few transponders, while others remain strong. I have been getting very low strength on 17 and 19, while at times getting no measurable signal from 25. (This is a very important transponder, as it carries ESPN and Fox Sports World!) While 17 and 19 are low, I get 100 on 18, although it only carries locals for elsewhere (outside Albany, NY).

Is this likely just me needing to repoint my dish, or have others experienced this, as well?