Did you check the tooth engagement on the starter gear, or just assume that it was right? I like to spray-paint a few teeth on the flywheel, then run the starter and see how much of the paint gets rubbed off. If the starter gear teeth are bottoming out in the flywheel ring gear, install shims until there's a small area of paint left at the bottom of the tooth contact area.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!