I would have got it right away, but then I might turn up there any time. 
The knobs I removed from my house were fastened with an unusual type of screw. Robertson drive, of course, this being Canada, but the threaded part of the screw is tapered over its whole length, probably to make driving easier in the days before power drivers.
The original wire nuts are glazed porcelain rather than plastic, with the threads molded into the ceramic.
