Follow Up on this one -- turns out I had loosened the screw already but it got kinda "soft-stuck" and just would not fall out of the hole (or turn any further). I almost stripped it totally but then poked around by trying steps 35-37 in advance, then I found I could turn the screw back inward (clockwise), then back out again, and kind of jimmy it out of the hole to complete the disassembly. I was VERY lucky that it was still usable for the re-assembly with the replacement part.
The lower left corner (yellow circled) screw has probably "screwed" us - for some reason it just won't start turning. Perhaps some glue under this one, needs heat? Anyone else faced this issue?