Dan -
That second piece is very informative - I now feel as though I have a basis upon which to proceed. I read it 3 times over my first dose of wake-up coffee ; there’s a lot of nuance and detail in there. It seems that the sequence of adjusting the striker is key.
After morning chow I will try adjusting the existing striker as per that procedure, see if I can’t get that driver’s door to work smoothly like the starboard side one. If I find I need to install the new parts I now know that the window guide gets loosened but the glass mechanism stays in place - that’s a relief!

THANKS for the lead.