Eric, I had this problem and I found that the blades had worn down to
stumps, we did use well grogged clay and it was in a college situation with
heavy use but it might be worth checking. After replacing blades everything
was fine.
Peter Linford
c/o Motor Yacht Alia'n, Hotel Intercontinental,
P.O. Box 36, Hurghada, Red Sea, EGYPT.
