Hand wheel spins without moving the needle
I have an older kenmore zig zag sewing machine. When sewing the needle will stop in the down position and then the hand wheel starts spinning freely without moving the needle. If I hold on to the inner wheel and turn the outer hand wheel backwards until snug it will sew for a little while before doing it again the especially happens when going through more than 2 layers of fabric or when you come to the vertical stitches on a hem. I thought that it might be the clutch, but then again I don't know for sure. When my machine does this it gather's the bobbin thread in a huge clump underneath. I know that my machine is threaded correctly so that is not the problem. I am a seamstress, but have never had a machine do this before. So I am stumped. Please help.
Sewing Machines - White Sewing - 1766 Mechanical Sewing Machine
Answers & Comments
I used to have an old Bernina that had an inner and outer hand wheel. Loosening the inner wheel disconnected the needle bar from the motor so you could wind the bobbin without running the needle up and down. It sounds to me like your machine has the same feature, but resistance on the needle makes the inner wheel loosen up. I don't know whether wrenching on it as tight as you can would be enough, or whether this is a symptom indicating that there is something loose internally in the connection between the inner and outer wheels. Good luck!