There - I fixed it.
It wasn't that hard, but your description helped. For anyone else who needs to disassemble one of these:
I started by using a jeweler's screwdriver to pry the loosest part of the light green locking tab away from the dark green half. Once I had that free, I used a small (1/8-inch ?) Craftsman standard screw driver which gave me more leverage. Looking back, I think once I had all three tabs loose on one side, I could have just pried it over, but I wasn't sure of that, so I just kept working my way around it until all six tabs were loose.
Slowly take the two halves apart.
The top of the dark green half contains a large fairly stiff spring, and a U-shaped set of contact brushes. Unfortunately, the brushes separated and I'm not positive how they were oriented. I'm pretty sure they went so the "tangs" angled down toward the base of the plunger. I think it would be obvious if you were looking at the switch anyway. The brush has two sets of contacts, so I rotated it 180-degrees so the unused ones were making contact, so I might get another 120,000 miles out of the switch.
There are also two fixed contacts in the dark green half, but these don't matter.
The light green half only contains the white plunger, a white collar, and a small "circlip" - actually more like a snap ring. I used my fingers to push the open ends of the snap ring apart, making a loop on the other side, then carefully used a very small jeweler's screwdriver to pull the snap ring off.
The plunger doesn't have fixed notches, it just has one notch at the bottom and one at the top and then something like hacksaw blade teeth to allow the plunger to ratchet to the desired length. (Thinking about it now, it might have worked fine to just grab the plunger with Vise-grips and pull rather than disassembling the switch).
I think Ford used the ratchet mechanism so that the same switch can be used in multiple car models.
Once you have the snap ring off, remove the collar, then re-insert the snap ring and lower the collar on the plunger to the upper notch.
Now put the contact brush back on, make sure the spring is seated, and snap the two halves together. I had a minor hiccup here where I broke one of the "ears with knobs" that lays against the mounting bracket off, but I don't think it's really needed, and I super-glued it back just in case.
Thanks again for all the help!!!