When you get to the stage below, I wouldn't remove the thumb lever's pivot screw (red arrow). Cody aka TheMotorcycleMD does remove the pivot screw in the linked video
https://www.youtube.com/watch?v=Ob4JWFQ6aTc&feature=youtu.be&t=784 to lube the parts. But the assembly can be lubed without removing the pivot screw.
I've found it impossible to tighten things just the right amount if you have to put the screw back. For example, is it tight enough so it won't loosen by itself after many miles? If it's a little too tight it'll create a drag on the thumb lever's movement. There is a shoulder washer in the stack supposedly to prevent overtightening but it don't work that well. If anything, just tighten the pivot screw a micro turn instead of removing it.
