How old are these pumps? Pump made since 2012 the metal rod should be permanently part of the motor and only the magnet and prop should come out. If it is older an assembly of the shaft with two blue bushings, disk and magnet and prop should be removable and if the shaft is stuck in the magnet, grasp it with pliers on an end that will be covered by a bushing and pull with a twisting motion. If it gets stuck further in, use a punch or a small nail and a hammer to drive the shaft through and then soak everything in vinegar until the lime is dissolved.