A thumb wheel mechanism includes a thumb wheel with upper and lower
surfaces, the lower surface including a bore with a ball connected to it,
and an handle half with upper and lower surfaces, the upper surface
including a divot, the thumb wheel lower surface being aligned with the
handle half upper surface so that the ball rests in the divot of the
handle half upper surface when the thumb wheel mechanism is in the
neutral position, thereby minimizing the compression load on the thumb
wheel mechanism.