OK, so I parked my 340 Utility for the night, and it wouldn't start the next morning. I looked over the usual suspects, and didn't have any fire at the plugs. OK, I thought, some of the wiring shot craps and I'll have an electrical issue to fix. So I chased an electrical issue that isn't there. It's all solid. OK, I thought, the cap and rotor are funky or worn or whatever. Nope. Solid. Points looked good too...I eventually just got around to the last thing- take a look with the cap off and watch its operation. Ta-da! My rotor isn't spinning. So, since the rotor/shaft don't spin freely, the drive gear must be good, right? What else in that chain of gears make the distributor work? Is there a shear pin somewhere? It's time to start mowing again and now the dumb thing lays down on me.

OK. So can I replace that drive gear? Is it plastic (sacrificial), or do I have to worry about its mating gear being torn up and metal shavings in the oil? I've not had a distributor out before, and I'm not sure what I'm looking to find.
I'm hoping against hope that the distributor is salvageable. I can't afford a replacement after I just put 4 new tires, a radiator, and a battery in my work truck...

If I remember right the drive gear is metal but there would be very little metal floating around in the oil since the gear is about as big around as a quarter. It has a roll pin holding it on so one should be able to pull it off and replace it. The gear on the cam seem to be a lot harder to hurt then the one on the distributor

I have a 340 row crop that pretty much did the same thing. Took a while for me to see the rotor not turning at times and other time it did. I could not turn the rotor by hand but some of the teeth on the distributor drive gear where bad enough it would spin one time then not the next. Took a distributor from one of the Hs I have and put it in and it has run just fine since. I bet if you pull the distributor and look the gear over at the bottom of it you will find some of the teeth sort of rolled over on it