if you look in the pic above, right below the black cable and to the right of the brass deal, you can see a little plug that screws into the hole. i dont know what the size is, maybe 1/8" NPT? if you go to a plumbing supply or hardware store you could probably grab a couple sizes and find one that fits. i did the same kit on mine and remember putting the plug in there but cant remember what came out of the hole originaly.