Thanks for all your help everyone. It was indeed a wick. I did manage to get it back in and everything seems OK, except for that thumping sound. I'm going to try changing the needle or see if it slipped down as debcavan suggested. I read my manual front to back when I first got the machine and several sections more than once. I don't remember ever seeing anything about a wick under the bobbin case. I am completely amazed. I'm gonna read it again to make sure there isn't any other surprises. Thanks again for all your help everyone. I knew I could get answers here, you all are great!