Well, I may be up for an award.
I put the 740 seats into the car (they aren't in bad shape, leather matches too) for now. Wanted to give myself some time before taking on the swap project.
Curious to see if the heated seat function works, I hooked up the battery I'd been using to work on the power seat.
The battery is/nearly dead.
That would explain why I was getting functionality from the power seat that just 'went away' with a few seconds time. The confusing part was there was just enough power to turn the motor for it to turn the cable, but not enough to power the chair movement. The back of the chair movement must have used a very minor amount of power.
I must have rebuilt the bottom of that seat 8 to 10 times looking for clues as to what was going on. At least I know it well now.
Wonder what will happen when I hook it up to the charged battery...