I inherited my Aunts 758 and it has been terrific. I was sewing a thick seam and thread balled up in the bobbin area several times then nothing would move. I took out bobbin cleaned and next as I'm sewing I notice that every time the needle goes in the thread is being cut so that a have a small mess of thread. I changed bobbins and needle. Still many small cut threads. It seemed that when I removed the bobbin the metal casement that holds the bobbin was wiggly. (It holds the bobbin in place and you push down the lever that holds the bobbin in place. Could this piece be broken? is it supposed to come out easily? I can't get it back in properly and move the dial tha moves the needle up and down.