My machine froze up.
I was doing straight stitch quilting with a walking foot using my Brother 1500. It stopped sewing with needle down. The wheel wouldn't turn at all to raise the needle. Got the needle out. I took the top cover off and found the problem a big spring at the top right had come undone and was blocking the gear from turning. I moved the spring out of the way and the machine wheel and gears were free. I have no idea what this spring does. The machine sews fine, the bobbin winds fine. Why on earth was it there in the first place. Anyone know? I'll take it to a shop eventually but it sure is a mystery.