Remove the screws from the motor cover
Fold the treadmill up and remove the screws from the rear roller endcap
Remove the screw on the outside of the endcap under the hole for the adjustment bolt
Use your allen head tool to loosen the adjustment bolts on the rear roller. This will give you some slack in the walking belt.
Rotate the motor flywheel while pushing the drive belt away from the motor. This will make the drive belt walk its way off of the pulleys. BE CAREFUL. You may want to use the handle of a screw driver or some other item to push the belt over as you rotate the flywheel
Remove the screw(s) from the front roller shaft and remove the roller