If you look on the bottom there are two arrows near back wheels pry there on each side with screwdriver and should pop right off. Then there is a housing for the belt that has two screws in it. change the light bulb since you have the base off.
Kenny B
October 2009
The cover to the base prys off from the bottom. There are no screws holding it on. It's easiest with a couple of flat screwdrivers. Look for along the edge of the cover (on the bottom) for a place to put the screwdriver to pry it away from the base.