I bought my XP3 last November I think when Big Al's Online was having that awesome $85 for an XP3 sale. I've had no problems since November, but lately it's not putting out as much. The filter media is fine, there isn't any noise or rattling, I don't see any snails or other stuff in the impeller or when you look through the input/output holes. The hoses seem fine though they have some gunk in them. What should I do or check?