The winding can open up and the side from the jumper can be the one shorting to the case and it not be protected. There is ALWAYS a case for fukkery.
Just put the correct heaters in all positions and don't question it. That's my policy.
Speaking of fukkery.....I started the little chinesium band saw on some tubing the other night. Then I turned and started working on a gate facing the other direction. The wife stepped out and said "um...honey...." The blade was locked and the motor was just a boiling out black smoke. Melted the motor to the ground. 20amp breaker never bobbled. Square D Homeline too, not that FPE red handled crap. It was an amazing show.
Now see, if I had a starter and heaters on it...that wouldn't have happened.