Arch, I just got through testing the strobe idea, and I think it will help.
I chucked a 16" wooden ruler approximately midway in the jaws of a spigot
chuck, so it was spinning like a propeller. Using the strobe, I was able to
make the image stop, or drift in either direction. I was able to read the
numbers on the ruler even with the room lights on.

My main concern is whether you can find a strobe light like this. Mine is
probably 40 or 50 years old--I got it as a junk or surplus item, and I
believe this is actually the first time I have used it. I'm sure there are
new units available, but at what price?