i was under the hood today washing down my dusty engin and found that the screw plug that u have to take out to adjust the star wheel is missing. i dont know how long i have been driving like this. well last time i messed with it was three weeks ago. does any one have a part number for it? also will it hurt if i drive without it, and if i got a little water in there is it going to mess it up?. i dont want to start it if it is.