Let me expand to save face ! The 500 head does not have feathering bearings in the sense of a " bearing " like the 300 has ie the bearing takes the load. the 500 has spigot bearings that allow the blade to feather, the load is taken by the TT straps. I still think your problem will be the uniball although if the spigots or rollers are stuffed then you will never track it