Russell Webb

 I took it to the Lowes where I bought The heads and three of them have no idea what"s causing it. They just gave me back the purchase price on two of them. The nut that holds the head on the  shaft is hexagon on the other end is embedded in the plastic head. The hexagon end that" embedded in the plastic is what is twisting out. I don"t know of a nut or washer or anything that goes on the shaft above it. The head just twists off and falls on the ground with the long nut stll on the shaft.