I finally figured it out. I called the vendor who had the set like mine. He told me (incorrectly!) that there was no screw, it was just a stud. After banging at it with a hammer for a while it was clear it wasn't coming out. I practiced my zen and stared at it for a good long while. There was a hole right over where it was binding, but no screw head. I kept staring at that hole until it finally sank into my thick skull that the hole was hexagonal.
Two minutes and one allen wrench later the hinge was off. I hate when I'm not minimally observant!
Thanks to those who offered suggestions.
For those who might have this problem in the future - here are a couple of pictures of the hinge off and one pointing to the hole that has the allen head.
A.J.
1974 Fiat 124 Spider
2006 Corvette
1981 Spider 2000 (sold 2013 - never should have sold that car)
