The needle needs to be in the center of the ruler foot, it sounds like you don't have the correct foot, I had the same
problem. Look on westalee web sit and they have pictures of the different size ruler feet for different type shanks. Good luck!

On My Singer the feed dogs don't drop. It has a small plastic cover that pops in. Always pops out at the wrong time too. lol. I take a old credit card from ads I get in the mail and punch a hole in it for the needle. then I tape it down. Much better. Not sure this is the problem just thought I would share.