You may need to replace your clutch. The belts tend to stretch of the course of time and then the roller brush doesn't turn as fast when you try to vacuum carpets or rugs. The only other thing it might be is the lower hose. If it has a crack in it, you'll be losing suction there and it would only affect the bottom portion of the vacuum, not the hose.
www.bobsroswellvacuum.com, October 2008