Thanks Caroline,
But, something strange is going on here. What you sent me suggests that the problem is insufficient pressure on the presser foot. "The pressure of the presser foot is insufficient, increase the pressure by pushing the head of the darner" What I have is just the opposite. I can adjust the foot pressure easily with a knob on top. With no pressure on the foot, it self feeds but the stitch length is way too short, regardless of the length setting. When I put even the slightest pressure on the foot, it stops feeding. I can pull it through with a gentle pull, but it won't feed. That suggests to me that the friction from the foot is enough to stop the dog from feeding. Is the dog just worn out?