Thanks for the attempts to help, Gang. But, you really have to have played with PAM clocks in the past to know what I'm looking for. I'll try to post a picture shortly. This item is a weird little nut that is not hex-shaped, but rather has a round, serrated exterior. And, it's an odd internal thread size. It's certainly not a thumb screw, and I've already checked the hand retaining nuts on some of the little imported clock movements. Wouldn't you know it....those nuts are all metric tread sizes.
Again, I appreciate the info in the posts to date, but I'm still lacking a solution, or the name of a vendor who might have these. Thanks. John