This reminds me of one time when I was back in college. I went over to my friends house one day (bunch of guys lived there) and their vacuum cleaner was sitting next to the front door. I sat down, had a few beers and watched the tube, then of course my curiosity finally got the best of me. I say "hey why is the vacuum cleaner out sitting next to the front door?" One says, "it doesn't work anymore so we are taking it to the repairman". Of course I couldn't resist this opportunity, so I sprang from the couch and ran to the cleaner. By the time I got there I'm asking questions..."what's broken?" the reply "well it runs but it doesn't pick anything up anymore. The first place I decide to look was to unzip the bagging area and see what's going on. Huh? the inner bag seams to be full. I say "have you tried a new bag? this one appears to be full" Blank stares throughout the room then "replace the bag?" yes, put in an new bag to catch the new stuff. Well you know the rest of the story...
Moral of the story....
Have you looked at your filter?