So here are my best examples of the screw head showing up in the margins on three of the 1898 Series Revenues Stamps.
I have other examples, but not as complete as these are.
Would really like to see if anyone has it a complete screw head.
The RB24 (U.S.S. Olympia, a Protected Cruiser) is the best one I have, almost, but not quite 100% showing.