Choke pulldown unit. Will open the choke flap a little once the engine fires up from cold. Probably not required unless you have to use full choke to start.
It doesn't. If the choke cable has been pulled fully on, and the choke flap is therefore fully closed, it will open it for you a couple of mm as soon as the engine catches and starts generating significant vacuum. If it wasn't there or isn't working, the engine would probably conk out almost immediately after starting on full choke, unless you are quick at reducing the amount of choke manually. If the choke flap isn't fully closed because you haven't pulled the cable fully on, the pulldown will do precisely nothing, because the flap is already beyond the pulldown's scope of movement.
