Hi. I've got seven deadbolts with weird fasteners and need some guidance. These are old Schlage locks, probably installed in 1966. One has hex heads; no issues. The others, however, have some sort of steel plug where the hex hole should be; some have round holes. I've uploaded a picture of each of these types -- https://imgur.com/a/hsisYE9
Anybody familiar with these deadbolts, and have advice on how I should go about removing them?
Absent a better Idea, I'll have to try prising the plugs hoping to find a hex head underneath. The ones with round holes, maybe try a screw extractor.