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

Take the engine Model Type and Code numbers to your local outdoor equipment shop. Tell them you need a Starter Drive Kit. It will come with a new pinion gear, spring, retaining pin or c-clip depending on what type your engine has. The kit should come with instructions as to how to rebuild the drive.

Rick, November 2006