Starter question John Deere B

Something is going on with the starting system on my 51 B. Sometimes you push the switch down, and the starter simply spins freely without grabbing the crankshaft. It can do this a few times before it will actually catch. When it does catch, it will spin the engine a few times before it makes a bit of a grinding noise losing the crank/overrunning clutch on bendix kicks in. This system has been converted to 12V, so it spins fairly fast.

I took the starter out, and the gear on the end of the starter seems to look okay. It will slide in and out okay on the shaft when the switch is depressed. I did notice some irregular wear on the teeth of the flywheel. One roughly a quarter of the perimeter of the flywheel, the first 1/4" of teeth are worn/ground a bit. I assumed this was not a huge deal, because it looks like if/when the starter is fully engaging the flywheel you have a good inch or so of gear engagement.

My question is the following: is there anyway to adjust the amount of engagement of the starter gear? Would there be any reason I would not be getting proper engagement? Is this wear on the flywheel unacceptable and causing the problem?

Please let me know your thoughts.

Starter drive is failing, even though the gear looks fine, it's slipping inside. It's possible the starter is starting
to turn be for the drive gear is fully engaged in the flywheel. When switching to 12 volts from 6 this is what happens.
A John Deere 50 Starter maybe a easy fix they were 12V. When you purchase a starter Drive, DON'T Buy a CHEAP one.

Thanks for the feedback. Would it be worth it to bring it to a local starter shop and have them take a look at it? Assuming what you are describing is happening would it be a serviceable problem or do I need a whole new starter? I will look into JD 50 starter pricing.

The starter motor itself should be ok. Sounds like the one way clutch (part of the starter drive) is slipping

re: starter not engaging. I personally would definitely take it to a shop that's reputable and with which you have "good will". There's a couple of other things that could be involved. With two cylinders the flywheel (and ring-gear) are going to stop turning on the compression stroke of one or the other when you shut down. So, when you start it, the starter is going to engage in one of those two places. Due to the firing cycle, they are very close together and the wear there is considerable. This is hard to see without removing the flywheel cover. If things aren't quite right after you have the starter looked at/repaired, have a good look at the ring gear. You can get a clue if you rotate the flywheel about 90* "using a suitable tool" before you try to start it. If it engages OK doing that, you may have a ring gear problem too. THAT is a female dog to fix, at least it was for me. If that seems to be an issue, post back and get some tips on flipping/replacing the ring gear. But. .. .I hope a visit to your starter shop will be all you need! Good luck.

Does anyone have any experience replacing the starter drive? I can order the part but have never taken the starter apart. Is it involved?

Replacing the drive is not a tough job but reassembly of the starter is the tricky part. The brush plate on the commutator the trickiest. Your starter is a Delco 1107942. The starters for a 50, Delco 1108144, 0r 520, Delco 1108155 are nearly identical. Buying a used starter is buying anothers problem. I have rebuilt dozens of those starters and can do yours if needed. I have the parts (drives, bushings, brushes, switches) in stock. I rebuild them as a hobby and have done hundreds of them. E me if questions.