Hello Terri,
If your machine is sewing in normal stitch length then suddenly goes into long stitches the problem will most probably be either a blunt or bent needle, the needle only has to have a slight burr on the end or be bent very slightly and it will miss stitches giving the impression that it is only sewing long stitches.
Ken
drivewithken@blueyonder.co.uk
Ken Dourof, June 2007