Is the needle shank round or does it have a flat side? One of my vintage machines takes a round shank needle and I go by the eye of the needle, the threading side has a longer groove than the back side. This particular machine threads from front to back, but with older machines it can just as well be left to right or right to left. It's definitely an advantage to have the manual for the machine. You could take off the needle clamp and check if there's any dust or grime in the grooves behind there. I had similar trouble with a Singer 201, needle scraped slighly against the race on one side and it wasn't quite centered in the hole in the needle plate. I thought it might be timing, needle bar off sync or something like that, but after I scraped out a lot of grime of the grooves in the needle bar everyting lined up perfectly.
Last edited by Mickey2; 09-29-2016 at 05:41 AM.