I am trying to confine a bearing shaft within a slot. It is a moving arm on a test fixture. It is in a slot that is twice the width of the sleeve bearing. Picture a rotating arm used to cycle a laptop. The slotted rail is on the laptop flap. As the arm rotates the bearing contacts the upper part of the slot, when it returns the other way it moves freely in the slot until it contacts the opposite side and then it lifts on that side. How do I confine it within that over sized slot so I can use motion.