One thing I have noticed, on my Sebbie and a few others, is some of the
screws do not fit the allen wrench very tightly, a lot of play, in this
particular knife, the clip screw shows being loose or too large an opening
while the other screws were ok, as I recently took the knife apart to clean
and lightly, every so lightly, polish the washer...

G2
edited to add, I did try a couple of different wrenches as well, no luck!