reference to fig4 the fulcrum lever 21 of the fulcrum lever block 2 can be introduced into the fulcrum lever hole 31 of the block 3 a retaining ring 24 serves to secure the lever 21 with respect to the thread block 3 screws 5 and 6 will connect and lock the fulcrum lever block 2 at the needle plate 1 by extending through the round holes 22 and 23 respectively whereby the front end of the thread block 3 projects from the front wall of the needle plate 1 as shown in fig4 and 5 the lower end of the spring 4 should first be inserted into the spring stay hole 32 of the block 3 the hook terminus 41 of the spring 4 is secured by screw 6 and a nut 61 but allowing spring operation of spring 4 thus the block 3 with its thread guide duct 33 at the lower edge of the thread block 3 is operatively attached at the needle plate 1 with the effect that guiding of a thread 81 is easy as well as preventative of damage of the needles 7 of the respective machine with reference to fig6 which illustrates how the assembly is installed at a sewing machine the needle plate 1 is firmly secured at the body of the sewing machine by means of the attachment or anchor hole 121 of the attachment part 12 please refer to fig1 and 5 accordingly the needle plate 1 is located near the needles 7 of the sewing machine and the lower edge of the needle plate 1 extends generally at the same level as the needles 7 with the front end of the thread lock 3 extending between needles 7 and with a small clearance close.