I have a Singer 401A that was in tip top condition until recently. I was sewing along at a fairly fast rate when the bobbin case came loose and raised up under the needle and jammed up the machine. I have taken it apart and it works fine as long as the case and bobbin are not in it. I think the part that holds the case in place is bent. It is hard to tell by looking but it does allow the bobbin and case to rise up. What can I do? Are there parts available? I really like this machine but don't want to spend much to repair her.