The tracking sensor is not along the edge of the running belt or is stuck underneath the running belt.
The tracking sensor spring bends easily or is damaged.
The tracking sensor is faulty.
Badly worn running belt and/or deck.
The tracking motor is faulty.
White nylon block is bad.
Coupler screws are loose.
The running belt needs a tension adjustment.
Check the position of the tracking sensor and align it with the edge of the running belt if necessary.
Replace the tracking sensor spring.
Access tracking diagnostics by pressing 9, 1, 9, ENTER, and then press RANDOM.
Test the tracking sensor by manually moving the tracking sensor spring and noting whether the display reads, "Belt too far left", "Belt too far right", "belt within limits" or "belt beyond limits".
Inspect the wire harness connections and retest the tracking sensor.
If the messages regarding the belt position do not appear, replace the tracking sensor.
Replace both running belt and deck (deck is double-sided and may be flipped if it has an unused side).
Center the running belt over the front and rear rollers.
Access tracking manual diagnostics by pressing 9, 1, 9, ENTER, and then press RANDOM, MANUAL.
Remove the left front endcap.
Using the INCLINE keys, operate the tracking motor.
Inspect to see if the nut on the end of the tracking screw turns. The nut should turn very slowly.
Inspect the wire harness and connections and retest to see if the tracking screw turns.
If the tracking motor does not operate, replace the tracking motor.
Inspect the white nylon block for stripped threads.
Inspect for loose coupler screws and tighten if necessary.
Re-tension the running belt. Set speed 2-3 mph. Try to slow the belt by applying pressure with your foot against the belt movement while grasping the handrails.
If the running belt slows, slips, or stops (and the front roller does not) adjust the tensioning bolt, located behind the user's right front frame cap, 1/4 turn clockwise (not to exceed a full turn). Test again and repeat adjustment if necessary.