Abstract: A flexible shaft transmitting the rotational motion of a motor shaft to a rotor adapter is protected from deformation by a shaft protector which connects the flexible shaft to the motor shaft. The shaft protector is concentric about and completely protects the flexible shaft as it extends from the motor shaft to the rotor adapter. The end of the flexible shaft connected to the rotor adapter and the rotor adapter itself are free to move within the lumen defined by the shaft protector. The shaft protector, however, prevents permanent deformation of the flexible shaft by preventing the flexible shaft from bending to a point at which permanent deformation would occur.In one important embodiment of the invention, a rotor adapter is provided with a plurality of grooves which prevent the rotor from jamming on to the rotor adapter.