I highly suggest replacing the whole unit as they usually have a hairline crack in them that you can't see. They replace the choke on a carb car or the waem up regulator on the older v-8's that mercedes have. Just take a screw driver and stick it between the fuel lines and it should come right off. Be sure to unplug it first. I always use the scews that were originally on it because the replacements are torx and a pain. I am not a fan of torx heads and therefore another reason not to like the M-cass garbage that they make down the street.