A friend has one of these, and just broke a needle. (can't find the small broken piece) and the bobbin holder is jammed. I can't see how it is supposed to work. clearly the unit is mounted to the shaft, but there is a tang that holds it from turning, and I cannot see how part can turn, and part be held by the tang. (and at the moment it is jammed, and won't turn). (We didn't get a shop manual with it, and I'm not sure I could handle the problem if we did. She did get a repair contract, so maybe we will have to ship it....) can you help with a blown up diagram of that corner of the machine???