What's the problem of error 1 on my york t520i treadmill that stopped working, I need your help please.

Error 1: Speed sensor error Turn the power switch off and on again to reset the treadmill. If the treadmill returns to normal operation, you may continue to use the treadmill. If treadmill does not return to normal operation, then call the dealer for advice.
ERROR 1 CODE This is a safety feature that can stop the treadmill from functioning. This error can occur because the computer is not receiving the correct information from the speed sensor located near the motor. As a precaution the computer stops the treadmill until it begins to receive the correct feedback. By performing a few simple checks, the error can be cleared quickly and easily, and the treadmill can be ready for use. The treadmill does not move and displays "ERROR 1" Switch off the treadmill at the mains, and then switch it on again. If "ERROR 1" still shows switch off and push the running mat round (1 cycle) using your feet. Then switch back on. If "ERROR 1" still shows, then UNPLUG from the mains and check all of the wire connections made during the assembly. (SEE BOLD PRINT) UNPLUG If the treadmill still does not move, then please contact the helpdesk. Doing this may reset the program error, and the treadmill will be ready to use. This should reset the sensor, and the treadmill will be ready to use. Once the cables have been checked, turn on the treadmill again. This should eradicate the problem. 1. 2. 3. When assembling, there are several cables that need to be connected. It is very common for these cables to look like they are connected when they are in fact not fully connected. Make sure that these cables are connected as tightly as possible. The connections may have come apart whilst assembling the treadmill. here is a link to your treadmill web site http://www.yorkfitness.com.au/uploaded/pdf_71T520i%20Treadmill_5562.pdf