If you're referring to the one-way clutch that goes in to the centre of the recoil start pulley, then the answer is that it unscrews.
In the absence of the proper wrench, it can be knocked round using a drift on one of the lugs. Re-install the wire screen screws first, to prevent the whole assembly from falling apart.
phil_saunders@bigfoot.com
Phil Saunders, August 2008