Need some help. The feed dog bar on my New Glenwood (National?) rides against a cam/knuckle on another bar that come from a connector at the bottom of the column. However, it appears it is missing some kind of spring or other piece that holds the feed dog bar against the cam. Anyone have any ideas what should be there? The machine is trying to sew, but the feed dogs just kind of bob around and don't move the fabric. When my DH holds the bar against the cam, the feed dogs move properly. Do I need a picture? If anyone has an idea, I'd appreciate it!!