I am not sure what is wrong, but do you have a Singer needle in the machine? Maybe it doesn't like other brands. Could it be slightly bent? Is it inserted all the way up? Yours is a slant needle machine, so does it take a special needle? Also when you put in the bobbin, the thread has to come off a certain way, clockwise, counter clockwise, not sure which as I haven't used a machine with an bobbin case in a long, long time. But I remember that it also has to click or set as it is inserted. Run your finger around the bobbin casing (the part that is in the picture) to see if there is a burr that might be catching the thread. Also check the throat plate for burrs. Change threads to see if that is the problem. I think the hook should be near the needle when the needle goes down so that it can catch the thread and make the stitch. Try to google a manual for your machine, or look at other manuals to see what they say, as the machine stitch is basically the same. I would not adjust anything from another manual as yours is a slant needle machine, but you might get some idea as to the problem and solution. Worth a try anyway. Good luck.