Before I had my prop rebuilt one blade would stay closed and one would open. This produced a lot of vibration and little, but some, horsepower. The pin had worn and I believe it would allow the center of mass of one blade to get on the wrong side. Therefore, spinning actually foced the blade to stay closed. Is there enough play in your prop that you can actually pull one or both of the blades past centerline when closed. My prop now is set up so that the blades do not even touch when closed. There is about a 1/4" gap between them.
