machine will not catch bottom thread to complete stitch--not straight or any decorative stitches. thread just stitches-actually catches about every one inch or so. it was skipping stitches, & making wrong stitch for what was selected on the dial, but now won't make any stitches. haven't sewed in a long time other that mending, but I'm really puzzled. don't think the machine came with a paper manual, just video & I don't know if I still have it.