Bought a used treadmill from someone we know. Worked at his house, brought it home and the belt won't go. The upper electronics work but the belt won't turn. Not sure if something came loose in transit to my house or not. Above the off/reset switch there is a hole that looks like it's a button or something but nothing is sticking out. On the inside there is a plug that has 3 wires going to it. I don't know what else to do to make this work again.