I put my new darning foot on the 401A and it doesn't work. This machine sews a nice straight and ZZ stitch (haven't tried any of the cams for other stitches) but it won't let me FMQ on it. I'm sad. Anything I should check on? I thought that raising the plate above the feed dogs was how it was to be done, but that didn't help so put the plate back in place and it still won't catch the bobbin thread. Not sure what to do next.