Make sure no one is standing on the treadmill. Insert the red plastic safety key into the key slot on the front edge of the console.
Press the speed increase button until the belt is running at 5.0 mph.
Kneel at the end of the walking deck. Locate the bolt adjustment screws on the back end of the machine. One screw is on each side of the belt.
Use the Allen wrench turn each bolt one full turn clockwise.
Step on the treadmill and walk for a few minutes to check for slipping. If the belt doesn't slip, you are done. If it does, repeat Steps 5 and 6 until the belt doesn't slip.