First check to see if the NordicTrack treadmill is plugged in. If the treadmill is not powering on even when plugged into a functioning outlet, it may have electrical issues. If the walking belt is not moving at a proper speed, it is probably not tightened properly and requires adjustment.
When checking for electrical issues, ensure that the treadmill key is inserted properly. Also check the fuse box for any tripped breakers. If the treadmill stops functioning during use, it may reactivate if the key is removed and replaced.
A walking belt that slows down when walked on is not calibrated properly, and usage in this state may damage it. Consult the model's manual for how to adjust the walking belt to the proper tightness. Use an Allen wrench to adjust the left rear bolt if the belt is misaligned. To avoid accidents, make sure the treadmill is unplugged before performing any adjustments of this nature.
If the incline on the treadmill does not adjust properly, press the Incline button and remove the key as it adjusts. After a few seconds, reinsert the key. The treadmill undergoes an automatic recalibration process, first rising to maximum incline and then lowering to minimum incline.