I had the same problem. I took mine to Maxwell Prop at Crystal (MCI). They were able to fix the prop on the plane in about
3 Hrs. It is the locks that hold from going into feather. The cost was under $500.
Sorry for the ubber-late response on this one. If they happen to be the newer style Hartzell propellers, the nitrogen charge in the cylinder in the hub has model-specific PSI. Hartzell suggests the propeller air charge be reduced to the lowest PSI value IAW with Manual 115N rev. 16 table 6-6 for the Cessna 310B for instance. NOTE: The air charge value is dependent on the ambient temperature.
Too much nitrogen in the cylinder will change the engagement of the locks in the hub and make them disengage earlier.