check the cable before you assume its the clocks... its the black cable that runs from the bulk head to the back of the gear box... its helt in with one big cross head screw. either the cable could of snapped, or worst case scenario, the end might have fallen off into the gear box, be cafeful when taking it out...
check teh cable, if in doubt replace, far easier than doing the clocks... if no success, then it is the clocks, and i dont envy you! think there is a guide to taking the clocks out in the maintenence section in mk2... not 100% though...
hope that helps!