Gary, a bit of trivia for you, an engine will stop in the same places, on a 4 cyl there will be 2 worn areas on the ring gear. 6 cyl will have 3 and an 8 cyl 4. These are where the compression of the next cyl in sequence stops the crank from turning.
The other issue, as the teeth on the ring gear wear, the ones on the starter drive also wear and since it is spinning as it is forced into the ring gear (more common on Bendix inertia drives and the Ford moveable pole piece starters), it plays milling machine to the teeth on both until finally the worn down end of the starter drive gear and ring gear reach a point where they will not engage. This sometimes is evident by a grinding noise, or even a grating like a bad synchroniser makes. The other failure is the overrunning clutch in the starter drive, it can fail, or stick in the freewheel condition. This usually manifests as a whine or squeal from it.
The more modern starters such as the Ford PMGR and the interesting ones some of the imports and Chrysler use along with GM, are solenoid shifted and the contacts that turn on the motor are not connected until the two gears have at least partially meshed, this alleviates a lot of the gear damage. Even a lot of small engines are going this way from the Bendix inertia drives to solenoid shifted starters, frequently with permanent magnet motors.
Bill AKA "LOBO"
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"Getting old is inevitable, growing up is optional"
Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator
Wife's 2011 Flex Limited
Daily Driver 2009 Flex Limited with factory tow package
Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413
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