The thing about the stop is that its not a "hard" stop. The idle screw is actualy spring loaded at the tip. You need to push the lever hard enough to hit the stop and then compress the pin. If the pin is rusted it may not work and you wont be able to use the lever for shut down till you free it. The other possibility is that your idle is turned up so high that even compressing the tip of the screw all the way doesnt force the rack closed. Check that idle stop screw and one way or the toher youll find you probkem.