Is She Dead, Jim?

Turns freely, starts right up, runs like a champ. No clue why teeth would have broken off.

Are you using the old flywheel? Playing the 2 in 300 odds or whatever that it won't land on a missing tooth?

Playing the odds for now at least, and realistically probably permanently. In a stroke of luck, just days before the Corona crisis hit, I had gotten my wife a newer car (not even registered yet!) to replace the Jetta, and then this happened! So the Jetta will now be our back-up car for when one of our other cars needs work, etc. Hoping it will serve in that role without breaking any more teeth. Just wish I could understand why/how teeth broke in the first place.

You said you put a rebuilt starter in the car. Did you buy the rebuild from an outside source autozone, Napa, etc.? If so maybe they sold you the wrong starter?

No, I had the starter rebuilt by a local shop, so barring some mixup or subterfuge there, it's the same starter that came out of the car, or at least out of one of the several tdis in my "fleet."