disposed between them in a well known manner an axially shiftable rod 46 having a head 48 controls the tension imparted by tension discs 42 and 44 to the needle thread by the axial displacement thereof a lever 50 having an axis along its length has a pair of laterally extending pivot tabs 52 formed at a pivot point thereof the lever 50 is pivotally journalled to the mounting bracket 40 by a pivot pin 54 which passes through an aperture in the pivot tabs 52 and is threadedly journalled to the mounting bracket 40 the pivot tabs form a fulcrum point about which the lever 50 may be pivoted one end of the lever 50 contains a slot 56 having an aperture formed at one end thereof for receiving the head 48 of the axially shiftable rod 46 a spring clip 58 is adapted to embrace the lever 50 and cover the aperture in the slot 56 after the assembly of the rod to the lever thereby restraining the head of the rod from passing through the aperture the width of the aperture is larger than the diameter of the axially shiftable rod 46 and smaller than the diameter of the head 48 of the axially shiftable rod such that arcuate pivotal motion of the lever 50 about the pivot pin 54 will cause the axially shiftable rod 46 to be shifted outwardly from the needle thread tension device 36 the drag imparted to the needle thread 38 by the tension discs 42 and 44 of the needle thread tension device 36 is proportional to the force imparted outwardly against the head 48 of the axially shiftable.