Oh boy, oh joy! I walked out this morning, the sun was just right and spotted a small white piece with a round socket at one end and a small brass roller at the other. After looking at it for awhile I figured out how fits into the main assembly, and that I must still be missing the spring that fits into the round socket.

After more study, I pulled apart a retractable ball point pen, took out the spring and fitted into the assembly. It fits and works perfectly!

I guess I now have a Mercedes-Bic.