Can you post a picture of the other side of your part?
Is it the 18 tooth drive ring?
View attachment 889937
So in this picture that oldtimer posted, where the large cogs are and the inner diameter that lip that sticks up is a sleeve that could be removed,,I highly doubt that sleeve was ever serviced without just a complete drive ring replacment ,,meaning finding a good used drive ring might be your best bet..
So after seeing The OP added pics,were'nt there before I posted,, looks like the gear you posted is still intact...Maybe check the other side see what you have there to compare ,,could be the last person to assemble it didn;t know either and just put it there,,,,