And make sure the needle is the correct length.
I had a fun time figuring out the threading and bobbin on mine, but once I did, it sews like a dream. Oh, and now that I have it threaded right, I tie on the new thread and pull it through instead of pulling the old thread out and rethreading. Oh, and it didn't help that when I was cleaning it, I put the little wiry thread thingy back in backwards...(Like my technical jargon?)