If you want to open the lower unit, which houses the spinning brush, the belt for the brush, and the wheels, the trick is to first remove the plastic housing that covers the front-light. It sometimes looks like an integral piece, but it snaps off by pushing in a bit on the clear part of the plastic that covers the light, then lifting off the rectangular housing that holds this plastic cover. Inside you will find two screws that hold on the bottom unit. Unscrew them. Then turn the unit over and use a screwdriver to release the one clip on either side (an arrow points to the spot.) Then you're in. The belt is a snap to change and needs no further explanation.
Ethan, September 2006