the rim portion 127 abuts the tops of the pole pieces 19 at this point the inner planar surface 129 of the cap 123 contacts all of the impact ends 131 of the print wires 89 and advances the print ends of the print wires 89 out of the front wire guide member 95 as illustrated in fig1 the print ends are then ground off in a common plane which is perpendicular to the axis of the wire guide assembly 13 and parallel to the planar surface 129 of the cap 123 the distance between the rim surface 125 and the inner surface 129 of the cap 123 is exactly the thickness of the impact end 85 of the clapper member 31 consequently the cap 123 can be removed and replaced with restraining screw 26 and backstop 28 in fig3 and 19 whereby the restraining screw 26 is advanced until the surface 133 of the backstop 29 is exactly in the same place that inner surface 129 was in at the time of the grinding in practice this is accomplished by advancing the restraining screw 26 until it abuts surface 135 of the wire guide assembly 3 in fig1 and then backing the restraining screw 26 off a predetermined number of turns fig1 and 20 illustrate views of a modified coil assembly 25 39 of the present invention in the modified coil assembly 25 39 a return.