at least one stator comprising {TAIL ~ stator teeth} and a coil operable to produce an alternating magnetic field exerting alternating axial forces on the buried magnet system that has a self centering force and {HEAD ~ a required stiffness} to reciprocate at a frequency near an alternating current supply frequency; and 
at least one stator comprising { TAIL ~ stator teeth } and a coil operable to produce an alternating magnetic field exerting alternating axial forces on the buried magnet system that has a self centering force and { HEAD ~ a required stiffness } to reciprocate at a frequency near an alternating current supply frequency ; and
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH