You should check your machines rotating floor brush and drive belt regularly for wear or damage. Replace the belt if it is broken or worn. The drive belt is a critical component of your vacuum that allows the brush roll to rotate and remove deep down dirt from your carpets.
If your machine is not cleaning as well as it had before or the brush roll has stopped turning, you may have to replace the belt. If you notice a rubber smell coming from your machine you should check your belt for any signs of wear. To change the belt, please refer to your models user guide for installation instructions