Step 7: Replacing the fuser gear
Take the fuser and turn it to the gear side. Remove the main fuser drive gear (the largest gear on the fuser) -- press the small tab in the center of the gear to release the gear from its metal shaft.
The metal shaft has a flat side which is specifically cut to fit with the groove in the gear's center.
As you line up and install the new gear onto the shaft, be sure to press down in the center of the gear to prevent the gear's center from popping out .
If the middle of the fuser gear does pop out, shown below are instructions for fixing the gear.
Line up the spring with the bump inside the gear; then swivel the middle of the gear so that its closest notch rests in the cavity of the gear. Press the middle down firmly to secure in place.