Does anyone know how to remove the handwheel from a White FR? There is what looks like a large screw head in the middle of it, but when I take a screw driver to it, it just turns the entire mechanism for the machine, it doesn't unscrew. I can make the handwheel disconnect and turn freely (as for bobbin winding), but I can't figure out how to get it off completely. It's nasty grimy and needs some TLC. :)