I agree with UFO Galore. It sounds like this machine was converted to quilting on the frame exclusively by covering the feed dogs. If I'm not mistaken, this machine is like the Juki, Brother, Baby Lock, and some others, that are straight stitch only semi-industrial that some people use for FMQing but they can still be used for regular sewing. And yours might be able to do regular sewing if the feed dogs were uncovered. Just guessing.