All being well it may just be stuck, take the top off the machine and squirt some WD40 on the stitch length mechanism, at the same time see if anything has come loose, when you alter the stitch length the stitch length should be okay for whatever size you want, put the stitch length on the largest stitch, this will move the reverse button out as far as it will go.
drivewithken@blueyonder.co.uk, August 2008
