Kevin,
Thanks for the photos... I don't have anything like that on mine. Those are the same kind of captive nuts at the other three positions on the hinge pocket and those holes are not round, they have a flat spot. The holes in my pockets at this position are perfectly round and show no evidence of ever having a captive nut.
As an interesting aside, there's a
MANUAL at the bottom of that page which I have and it makes reference to there being 4 bolts on each hinge.
