Lower the cleaning handle and lift off the cleaning tank from the main base of the Bissell unit.
Use a standard screwdriver to remove the screw holding in the front nozzle. Set the nozzle and the screw aside.
Use the screwdriver to remove the two black screws holding in the clear end cap on the base of the unit. Remove the end cap and then unscrew the silver screw.
Lift up on the pivot arm and remove the arm and the small brush belt.
Pull the brush rolls off the metal rods.
Replace the brush by sliding the new brush onto the metal rod, making sure there is a washer on the other end of the brush.
Reattach the long belt on the bottom of the roller brushes and then replace the small belt over the back roller and the metal cog.
Set the pivot arm back in place and return the silver screw. Replace the clear end cap and return the black screws. Latch the front nozzle into place and return the screw.