I am new to the featherweight world, as I recently purchased a lovely machine that was operating with a nice stitch. I ordered a new belt, thoroughly cleaned it, oiled it, put the new belt on. Now the bobbin won't stay in. The thread comes up to the top and the wheel turns freely. I have studied the diagrams regarding reassembly of the bobbin case, and everything looks right. The bobbin doesn't seem to "click" when I put it in. Does anyone have any ideas? If I try to sew, the needle goes up and down and then the bobbin falls out.