I have a Craftsman 536.772300 edger (4 HP, 9 inch if that matters). The recoil starter rope broke. I pulled the side cover off and can thread the rope back in and I can wind it back up, but there's no resistance from the spring. The pulley spins freely in either direction. When I re-install it, if I pull the rope to start the engine, the rope doesn't recoil. I have the manual and it includes a diagram of the recoil starter assembly, but I don't see how to wind it with string resistance. Do I need to just replace the entire assembly? Any help would be appreciated.