I've gone through 4 side brushes so far and this has happened to every one of them. Sometimes I have 1 bristle left. Usually lasts several weeks. They seem to be too hard plastic so they break and break easily. Definitely don't buy these side brushes. The two extractors seem to work well, they are noisier than the iRobot extractors. So overall a pretty lame product. The air filter is an air filter, so there aren't too many problems with it.