Hey ByronM,
I have the griot's jacks that you mentioned and had the same problem UNTILLLLL I learned how to use the thing. Simply trust the jack and TWIST THE HANDLE ALL THE WAY TO RELEASE. The jack will lower abrublty for the first centimeter and then smooth and easy the rest of the way.
I have two of the Griot's jacks and wouldn't trade them for $$$.
Regards, Tittle