how do i even open just that part of the gauge....i know that if i mess up, i have to get a new one...right?.....i could open the gauge up but i can't seem to take the pin (the thing that u push to zero out after u refuel) out...also, i know there is a green slot where im suppose to put in a wire, but my car don't have that green wire for that green. i don't know what to do.