[ford38v8]

Russ, Like you, I've not actually seen the jam up. I do know that Bendix springs can break, and ring gears can get chewed up and/or out of alignment on the flywheel, and I also know that a 12v battery can cause these ailments in short order. A quick thing for you to check is the tightness of the two starter mount bolts, and that the small brace is installed from that inside bolt head over to the pan rail.