The Stitch Length lever is in the center of the tower. All the way up is longest stitch (5 mm); all the way down is reverse. The lever has a screw handle so you can "lock-out" stitch lengths -- ie, lock it at 3 mm, and when you push the lever up, it won't go any further than 3 mm.

You see a block knob at the bottom left of the tower. That disables the feed dogs for free-hand stitching. The roller pulley at the right of the tower is used when guiding the bobbin thread. you will have to remove the screws fitted on the screws and disengage the locks to remove the cover.

thanks.keep updated.