tang 103 which is received in a bifurcated portion 98 of a driving stud 97 contains a threaded hole which receives a screw 105 having an elongated head portion the link 73 is shown connected in fig1 to the driving stud 97 the screw 105 extends through the threaded hole in the rectangular collar 102 and firmly attaches the collar to the needle bar 74 located on the front side of the rectangular collar 102 and supported on eccentric collar 109 held positioned to the rectangular collar by a screw 110 is a latch lever 111 the latch lever 111 has forwardly extending ear 112 spaced from the eccentric collar 109 and a rearwardly extending lug having a latch surface 113 located a sufficient distance from the eccentric collar 109 to clasp the lower edge of the bifurcated portion 98 of the driving stud 97 when the bifurcated portion is in intimate contact with the lower surface of the rectangular collar 102 adjustments for proper clearance between the latch surface 113 and bifurcated portion 98 are provided for a rotation of the eccentric collar 109 on which latch lever 111 is supported and tightening of the screw 110 to hold the eccentric collar 109 in the selected adjusted position also supported by eccentric collar 109 and biased on the rectangular collar 102 is a torsion spring 115 the torsion spring 115 biases the latch lever 111 in counterclockwise direction as viewed in fig2 thereby to engage the rearwardly extending latch surface 113 onto the bifurcated portion 98 of the driving stud 97 opposite the screws 105 of the rectangular collar 102 is a post 117 extending from the collar 102 which post 117 contains a peripherial groove 118 on its end the peripherial groove 118 receives.