reference to fig3 and 8 the numeral 20 is a clutch solenoid secured to a support plate 21 which is secured to the bracket 4 together with the pulse motor 5 the numeral 22 is a solenoid plunger formed with an axial groove 22a at the outer end thereof the solenoid plunger 22 is connected to a feed control shaft 23 by means of a connecting plate 26 which is inserted at one end into the axial groove 22a of the plunger 22 and is at the other end inserted into an axial groove 23b of the feed control shaft 23 and is connected at both ends thereof to the forms and the latter by means of pins 25 25 the feed control shaft 23 is placed in a bushing 24 and is provided with a flange 23a at the outer end thereof as shown and is axially displaceable together with the solenoid plunger 22 the axial movement of the feed control shaft 23 is limited in the rightward direction by means of a stop ring 27 secured on the shaft 23 a u shape element 28 is loosely mounted on the bushing 24 and stradles a part of the bracket 4 the wall 28a of the u shape element 28 is pressed against the flange 23a of the feed control shaft 23 by means of a spring 29 which is mounted on the bushing 24 between the wall 28a and a part of the bracket 4 in this.