I had the woodruff key break on my gpx crank, it also broke a chip off of the crank sprocket, the crank pulley had disengaged itself yet again, after trying to build the end of the crank, although the woodruff key sat well in the crank shaft slot, and once the crank sprocket had been gently repositioned with an ally drift and a hammer i still found that there was not really enough of the key left sticking out to have any kind of grip on the crank accessory pulley, therefore i decided to drill a hole and plug it with a 1/4 drill bit that i had cut the solid end off of. if you have a wobbly pulley just try this, i've heard some people trying to weld it etc etc. .......Happy driving folks
(1995 Black GPX Auto Kent UK)