Hello Heather,
Undo the screw in the stop motion wheel but don't take it completely out, unscrew the stop motion wheel all the way and take it off, you will see a three pronged washer, take the washer off and put in a different position, put the stop motion wheel back on and screw it all the way up but don't over tighten, then tighten the screw in the stop motion and try, you may have to change the three pronged washer round a couple of times but you will do it, any problems e-mail me.
Ken
drivewithken@blueyonder.co.uk, August 2007