CHeck the belt as Dan said. Changing, checking the belt is not hard to do. Occasionally my belt slips and you will see smoking.
To check, first make sure that the vacuum is unplugged.
Then locate the screws that hold the front part (near the light if you have one). This will be on the bottom of the vacuum. Follow the screw pattern, and you will eventually have the face part off.
Then you will see a metal prong thing that the belt is settled on. You will be able to see if the belt is broken, or slipped off. If you have an extra belt its super easy to replace.
Then you have to rescrew it all together.
Its pretty easy!