I just like to share a kind of modification I have done on a Singer 237 domestic machine. With this machine I try to make sew with V138 polyester thread, and it fails (of cause). The upper thread gets damaged when I try to sew more than 5 stitches, and then the thread jam or break. So I tried to figure out why. The Singer 237 have got an oscillating shuttle, and it is a zig-zag machine. The Pictures below illustrade the modification: The modification fixed the problem, and now i