Check the tube that leads down to the brush head for clogging as well as any motor or HEPA filters. If that still shows nothing, take the cover off the brush head (like you're changing the belt) and look for obstructions in there. Usually, if you have low suction on the accessory hose, the problem is with a motor filter, HEPA filter, or a clog where the hose goes into the unit. If you have good suction on the accessory hose but none on the floor, it's usually in the brush head (clog or broken belt) Good luck