A belt is known to stretch and begin to slip after a certain amount of time/Also depending on use.
Try adjusting your treadmill belt, there should be two bolts on the right and left rear side of your machine.
Make sure to keep track of how many turns you give to each side, since you are tightening your belt you will be turning the bolts clockwise. Making equal turns on both sides.
After each adjustment, check the belt by pulling up on the belt from the center, you should not have too much space between the deck and the under side of the belt.
Once you feel the belt is tight enough, run the machine at a low speed.
Check to see that the belt is not veering off too much to one side, if it is moving over too much to one side this can cause fraying and damage to the belt.
Certain treadmill models have a safety feature that stop the machine when they know something is wrong, it could be that there is a problem with your main control board (Circuit Board).
You can remove the main shroud, and verify that the circuit boards LED's are on and that there are not any visually burnt or damaged components. If there are any, that could be a good indication of something being wrong with the board.
If you find yourself needing any further assistance beyond that point we would be happy to help you out! Our Technical Support Team is available through chat at www.sportsmith.net
or by phone 888-713-2880 we hope this helps and we look forward to hearing from you!