also to what ben has said. if the belt looks in order. check the small clear hose if it has a split in it, this will stop the brush from rotating, and with the hose being a flexible hose a split is soon missed.
John
john, March 2006
Is this an all floors version. If it is there is a round knob that you can turn the brushbar on or off. Check to see if it is on. If not there is a big belt which you say is ok and there is a small belt under a cover. take the 3 screws out and check this belt. if this is not ok then the clutch is faulty and needs to be replaced. also pull the ends of the brushbar off by holding one end tight and turning. see if there is any dust or hair caught up.