Mr Langdon's instructions don't address this problem specifically, but he does mention that the shaft should slip in easily and once in place should have a certain amount of up and down free travel. I haven't had any problems yet, but I've only had it a couple of weeks. Sounds like something to keep an eye on.

-Tim
'51 Chevy 3104 w/'56 235, 848 Head, HEI Dizzy, Corvette Cam, Split Manifold and Dual Carter YF's