I found that a good tightening of the head set screw eliminated the side to side head play in my flex 120xp's. They also still flex freely, with no noticeable extra resistance from the tightening.
Thanks. I'm going to dig in to them a bit further and see what i can do. For the price, they're pretty tough to beat. The 1/4 has no play at all and the more i use it, the smoother it gets.

