Need New Starter? (continued)?

I removed the cover around the top of the starter and saw that it is turning - but not engaging the flywheel.
The loud noise is probablly ok as it is going faster than normal with no resitance.
The teeth look worn but not so bad. It look more like they are not quite high enough to make good contact.
Also I can't tell if the gear can be easily replaced without also replacing the starter?

Jhno Tractor
November 2006