If the motor is turning the chain drive sprocket when you apply pressure to the pedals then as flecc suggests, it is very unlikely that you have a mechanical fault with your motor. It sounds very much like the fault which I experienced. This was the motor being stuck in a very low mode of power delivery. This was much lower than the minimum of the three selectable modes which are available. Changing mode on the handlebar selector made no difference to the motor output. Apart from this, all other outward signs were that the motor was functioning properly, just no, or very little assistance.What was the solution
Unfortunately, due to the sealed nature of these motors, the solution was a replacement unit.