Check for power source problems.
Plug the treadmill into a different outlet to eliminate the first outlet as the issue. If you know which outlets are on separate fuse circuits, try using an outlet that is powered by another fuse. Plug another device into the treadmill's outlet to see if it works.Examine the prongs on the treadmill's power plug to see if they are bent or distorted in any way. Check the connections between your power adapter and the equipment. Some models may need to be opened to complete this step.
Unplug the treadmill from its electrical source.
Troubleshoot running belt issues
Spray a towel with cleaning solution and wipe down the belt. Begin at the top and tug the belt firmly to move it downward. Dirt and debris can collect on the belt, which can slow it down. Debris can also drop from the belt into the interior of the treadmill. Adjust the belt so that it is directly in the center. Belts can stretch and begin to lean to one side after frequent use. You can try repositioning the belt from the outside of the treadmill by pulling gently away from the slanted side, but a technician should look at severe belt issues. Lubricate the belt by spraying a towel with silicone lubricant. This reduces belt friction and can lengthen the life of the belt. Replace the belt. Make sure it is the correct model for your treadmill.
Check the motor.
If the display console is flashing error codes, check these codes against the owner's manual. This should tell you where the motor is failing if it is failing. Open the treadmill according to the manufacturer's instructions with a screwdriver. Inspect the motor's connections. For non-experts, inspecting a motor might be fruitless. If nothing strikes you as being obviously wrong, you might need to consult a professional. Replace the motor. Treadmill motors can be purchased at exercise equipment outlets both online and in physical stores.
Check the speed sensor.
The speed sensor helps move the belt. If the belt is jerking or not increasing in speed, the sensor might be dirty or becoming detached. The sensor is usually in the interior of the treadmill's bulk, near the belt. Consult your owner's manual for the exact location on your machine.
Do not work on a treadmill while it is connected to a power source. You could be electrocuted or the treadmill belt could begin to move unexpectedly.
Do not use a treadmill that is not working properly.
Do not open the motor if you want to retain your manufacturer's warranty.
Repair the belt
The second way that comes to my mind on how to fix the treadmill is to use a material similar to the belt and a strong epoxy glue. The tire of a bicycle can be easily modified to fit small tears and with good use of the glue you can make it look like it never broke.
If your treadmill belt has big tears in it you need to either replace the belt or replace the treadmill. The latter being of course the more expensive option, and also the easier one. You need to measure your belt to make sure that you are getting the correct size, also contacting the manufacturer can help you in this since they are usually selling spare parts. When you replace the belt, make sure that you use enough treadmill belt lubricant to keep it moving smoothly.