Took apart a Leopard starter motor. Between any of the ten contacts, got about .7 ohms. A couple of ideas. First, the insulation on the windings is melting do to extreme heat. Possible causes could be too much current to the starter or maybe a poor ground. Taking one of your busted starters apart and see if it smells like an electrical fire.
The other possibility for the failure could be physical damage. I’ll guess, since I have no proof, that if the motor was spinning without a load, that it could tear itself apart. Could your starter motor still be running after the engine starts and the bendix has disengaged?
LAD Specialties customer / tony kart / rotax / kt100