I would start by performing all resistance checks in the manual and test the hall effect sensors in the stator. Also, cranking voltage from the battery is critical. This can be a problem even with a new battery if it is not a good quality one or it was not set up properly. Lastly, I had a problem with mine losing power and not revving. It turned out to be caused by corrosion in the connection between the stator and the harness that goes into the electrical box.