The two screws of inner kits (bottle opener, scissors, etc.) are hard to be screwed, so this work is only be called "semi" one.
I think disassembling is a useful cleaning way.
Assembling is much harder, because it's diffcult to match the long screw nut into the hole of the clam.
Finally I found a way: use a T10 screwer to screw the nut, then it inserts into the hole at a certain angle.