I would put the new starter on and try it. If it works and sounds ok, I would leave the gear alone
I agree with Charlie. don't go changing stuff unless you have too.
It isn't that precise that you have to be concerned with it. Also, you typically void the warranty if you take it apart.
Leave it alone, and put the whole new starter on, that's what I did with my 78 F-150 is put a whole brand new starter fresh from NAPA, and it seems to work quite well, and also check your starter solenoid and battery cables.