Unplug the Eureka 5843. Press the handle release lever at the base of the vacuum. Lower the handle to the floor.
Remove the two screws on the top of the brush roll cover. Lift the cover off the vacuum.
Lift the brush roll out of the base. Slide the old belt off the brush roll and motor shaft.
Thread the new belt around the motor shaft. Loop the other end around the brush roll.
Pull the brush roll away from the motor shaft to stretch the belt. Insert the brush roll into its previous position.
Rotate the brush roll by hand to ensure that the belt is seated properly. Replace the brush roll cover. Reinstall the two screws that hold the cover in place.