Mission accomplished! Took me a long time over the weekend, I went very slowly and methodically to make sure I didn't damage anything. Only minor thing was one of the clips for the A pillar trim panel fell inside the frame while I was re-installing, not a big deal.Maybe it is time you considered replacing the Blend Door Motor. Look at the repair instructions in the below link.
It might look like a headache to do but it really isn't. Just 15 or so screws hold the top skin (very light) on and everything is exposed.
Also, if you intend on doing it, I would suggest buy the OE motor as you do not want to do this again in 6 mos.
The new OE motor (from parts.com) works fine. I did have a bit of a scare when I first installed it and tested the AC with everything still disassembled, and it moved to the hot position and stayed there. Then I realized the temperature sensor (on the Low Range switch panel) was disconnected, re-connected it and hey presto the blend control started working. Not sure what was up with the old motor. Disassembled it and no broken cogs, so I guess the motor must have burnt out.
I'll post some additional tips with pics later that might be useful to others attempting this.
On to my next project, a faulty switch in the interior dome light, and bulb replacement in the trip computer. Already see some threads on those...
43sqd, thanks for your help!