Starter motor

I have some wear on the starter motor teeth that engage with the ring. Wear Appears at the ends of the teeth what is the excepted allowance or is it just a case of replace when it no longer engages.
Thanks

Take a step back and think of your project in one of two ways. I had to do this when I got the wife's TO-20 delivered and it had the starter hanging off the side of it connected only by the starter cable. She came out and looked at it and told me I had to be kidding. I got it pull started with no problems and ran it down the road. It had low oil, pressure, smoked a fair amount but it ran. I got it home again, shut it off and told her that she had about three choices. (1)Use it as is, pull start it when you need it. (2)Fix it as it minimally needs to be repaired. (3) Give me that brand new credit card and step back.
Well, not one bolt has been left un-turned and I am still not done with it. Oh yeah, it starts, runs and drives. No smoke, 40 plus PSI oil pressure, no noises, Now has about 77 hours on the electric hour meter I added. It has been modified in a few ways and has become a large toy. She stopped counting about the time the credit card got maxed. I stopped a bit after that and am now changing my mind as to what the finished product will look like. Master disconnect on the electrical ground circuit, Fire ext mounted on the 3 point link, sliding adjustable seat, electric fuel shut off solenoid, fuel gauge, amp meter, volt meter, idiot light, water temp, hour meter, Then we can get into the current 24 forward gears and 6 reverse. I have an Everett that needs to get added and that will make a total of 48 forward gears. 12 reverse. Huh?
Usual 4 speed transmission, X 3 range Hupp X 2 range Howard X 2 range Everett. That might get me down to 12 inches per hour. Now you can talk about your seat time.
"Been out plowing the lower 10 for three months now..."
I might do a 12 volt conversion on the 6 volt genny and run the Ferguson proof meter off the back of that as it was when I got it. Just a slight expense I am still thinking about. I like the 12 Volt as the starter spins faster and the engine starts easier. As long as the engine is properly tuned, the 6 volt starter can live on 12 volts. Just don't go crazy cranking it.

Where does this leave you? Figure out where you want to go before you start. I have had a few machines thru here that have come in, been worked on, cleaned up and sold for a few bucks more than when I started. Not her Fergy. That is just a dirt money hole. Similar to the boat... A floating money hole. Another story for another day. You can go cheap and do it twice. Think of all the practice you will get and the time you will spend doing it twice.

Then there is the metallic red and dark gray paint job that I will also get redone, her machine never quits.
I could go to plain gray. As long as it is metallic in there somewhere.... Hold still foot while I shoot you again.

Heck you right but that's me, I charge off with such excitement that the whole project becomes overwhelming and before i know it I will have it stripped down into a thousand pieces. I do suffer from this fixation that every thing must be as it was when it rolled off the production line. I will take heed of your experiences as i dont think the wife will take kindly to being put on the back burner while I spend whats left of my life out in the workshop talking to my little Fergy.
Cheers