when i was having my problems, my starter sounded like it was trying far too hard, started with a very hard heavy metal sound,.......much harder sounding (the only way i can describe it) then "others", and then 20 or so starts later, the teeth would be missing the starter here, or there, then everywhere after another 20 or so starts. once i swapped out the whole flywheel, with the one i had, which had a 3cz part number, all worked great. mine had been using the larger size clutch pad, etc, but once i changed that, might have changed the bellhousing too at that time, cant remember now,........but i ended up having to switch out the lever that moved the throw out bearing too with the one that came on the bellhousing from the "new" flywheel also........then all works great now, and has worked great ever since.
hope the new flywheel helps out your problem, keep an eye on it though, and if it sounds like a heavy metal on metal clashing kind of sound, then you might still have a problem.
i've got you beat,..............i had to go through 9+ starters, before i got my problem fixed,.........i had/ have 2 "lifetime" guarantee starters, so i can swap them around for the rest of my miserable life...........they remember me now by sight....... he he