I had one go and it just happened with no notice....one second I was cruising down the trail and the next I was coasting to a stop....no spark.
I also had one where the flywheel inner ring started to cut the wires. When this happened, it would sort of stumble and I had a hard time getting it to go into reverse. Took it apart and saw the cut wires. I pulled the stator out, cute the wires completely, soldered the wires, used heatshring and put the stator back together. I also used 2-part epoxy to fix the flywheel. It's been working great ever since.
I also had one where the flywheel inner ring started to cut the wires. When this happened, it would sort of stumble and I had a hard time getting it to go into reverse. Took it apart and saw the cut wires. I pulled the stator out, cute the wires completely, soldered the wires, used heatshring and put the stator back together. I also used 2-part epoxy to fix the flywheel. It's been working great ever since.