1. First, check your height setting. A height setting too low will cause friction between the brush and the flooring, which can put a lot of stress on the belt, causing it to break.
2. Check your brush roll for any hair or debris that could be cut off. Then with the machine unplugged, see if the brush turns freely by hand. If it does not, then a new brush needs to be ordered.
3. Keep in mind that belts break over the course of the normal use of your vacuum. They will need to be replaced periodically.
4. Beware of knock-offs! The only way to be sure to get a quality BISSELL® vacuum belt is by going to our website. You can order one by clicking here: http://www.bissell.com/replacement-belt-for-upright-vacuums-2031093?productid=6594