As I have mentioned before, my keel is left suspended about halfway up/down when on the mooring and lowered when sailing. Even so, when I go to raise it, the first 2 or 3 turns are extremely difficult and only become easier as it starts to be raised.
My only suggestion, for what it is worth, is that you move into shalower water so that it gets a nudge to get started!
Anyway, good luck