[SoTxButler]

I had that happen and it turned out that one bolt was loose and allowed the starter gear to torque and it began eating some teeth. Did not happen like you describe, mine just wore out the ring gear a little at a time. I replaced the ring gear, made sure everything is tight and so far...so good.

As Brent points out...something is causing that to happen...loose, mis-alignment, something.

Good Luck.