While you have the starter off check the teeth on the flywheel. Generally the steel on the bendix gear of the starter are softer so they are what wears out before the flywheel ring gear but it still can get worn. Also if you go to buy a new starter make sure to pay a little bit more and get a lifetime warranty one. That way if it happens again you won't have to pay for one again. Ive got an old ford dump truck that Ive had to replace the starter 3 times for the same thing your going through but on a ford there are no place for shims or room for adjustment.
PS Whats up with that avatar picture

PS Whats up with that avatar picture