The one I'm working with is the Low Idle adjustment screw that sits on top of the carb parallel to the engine block. It is accessible from the front , but with the air filter housing in place, it is a little tricky to actually see what you are doing. Taking the housing off to totally exposes the screw allows too much air into the mix, and the engine runs really rough, which makes it difficult to properly adjust. I don't have a picture of it at the moment, or I would copy and paste it here.