They get matted up with lint and dog hair, at least ours does. You have to pull them out and take the brush assembly apart and clean them. The brush holder pops out, try to do it straight if you can. Then the clear plastic comes off the black part using a screwdriver in the holes on the sides to them it to release. Ours just broke the green square plastic rod that turns the brushes. That could also be your problem.
Bill, August 2008
