I pulled out the parts diagram and took a look. On the 6", the ball and spring are located in a pocket in the crank. The ball drops into a depression on the face of the casting. The collar is what provides the force to activate the detent. Your problem may simply be that the collar has slipped. Loosen the set screw and push the crank handle tight to the casting face. Push the collar tight to the inner face of the casting and retighten the set screw. If this doesn't work, maybe the pocket needs rework or a stronger spring may be necessary. (it is possible that someone had it apart before and lost the ball and/or the spring. You should feel the detent when you rotate the crank.)