Are Interior blades supposed to move or br stationary?

My unit turns as I can get a socket into the top and it spins freely. However there are two "blades" inside the unit. One turns freely and the other does not. Would this bind up the motor? If I turn it on while spinning the main nut that I can get my socket on to it starts to go..... Should the blade that is moving be stationary or should both blades be moving?