Most of the time, in my experience , check the simplest things first. The belt might need to be adjusted. The next thing I would check is the lid switch and it's plastic activation tip. Sometimes the switch itself can move out of adjustment. If this is the case use a small wooden dowel or a plastic spoon handle and push down till it you hear a click. Be gentil and try several times. Be sure that the timer has moved to the proper position or nothing will work