Not sure why but my airborne 101s have the string off center on both cams. I was working with a reezen today and the top was centered but the bottom was really off to the side. If you think of the mechanics, why not just center everything? Sure would make a laser more useful. I guess that I should say that I am a bit anal about tuning. So that question becomes do you set your rest in the center of the bow or inline with the plane of your string path? I just tune and tune and tune until it is perfect which takes awhile sometimes.