Burning smell is from the belt that turns the brush. Most the time hair or carpet fibers has it jammed up. Unplug vaccum. Turn it upside down and cut the tangled mess and remove it. Alot of the time the vaccine will be plugged up behind the brush and before the fill basin. Also remove the hose attachment and check from there to the are that makes contact with the floor behind the brush. Use a metal coat hanger to remove clogs. Dump basin and remove filters. Wash them or beat them against something outside to release the dirt. Put it all back together and do some house keeping.