I was just wondering - the screw that holds the bar in at the bottom of the trem can make the bar loose or tight. Then, the allen screw on the collar can also tighten the bar.
I always assumed you tighten/loosen the bar's swing using the underside screw and the nylon collar at the top was purely to keep the bar from moving around laterally within it's socket. Either way I keep both tightened moderately on my Luke 1.
I actually found it's easier to remove the underside screw, and keep the collar screw tight enough so the bar doesn't fall out. That way, I can remove the bar when I want.