I posted this question a couple of months ago, but no one had dealt with a manual seat recliner since their 240 or 740 days. I have now figured out the answer myself. (It's a nice sunny day, and I could get a better sense of what I was doing.)

Unlike the old models, the entire recliner knob simply pops off (just work it off gently), and there is a nut in there. A 10mm socket works nicely to adjust the tension.

I hope this helps somebody else out there.