I was looking for the same answer today...and found this online at a different cite...maybe it will work.
1) disconnect the cord from the electrical outlet.
2) remove the four screws at the corners of the brush opening on the bottom plate.
3) replace with new belt
4) slide belt over motor shaft, then slide belt over large pulley while rolling pulley towards front of vacuum.
replace the cover and screws.
Emily
March 2008