Think I figured it out. I was using an old but previously unused alkaline C-cell for the glow plug. When I tested it before going outside, the plug lit up nicely, and the battery seemed to have a lot of life. After going outside, getting set up, stopping for lunch, etc., the battery must have cooled off sufficiently that there was little juice left. I used another battery from the same package, and--no surprise--no joy.

Tomorrow should be 65 degrees, I'll have a fresh battery as well as a good attitude. I'm sure it'll start.

As a guide--how many amps should the OS type F draw when energized with 1.5 v?

Thanks for all the advice. I have some ether ready in case it remains recalcitrant.