I know it probably fell down and I didn't see it but that's not what happened trust me. So I go to take out the stock fuel screw and do it very slowly so I can see each part come out and I also put a large box right under the area as well with my other hand cuped right under the fuel screw. As I'm taking it out I see the screw first then the spring then the washer but no oring come out at all I then installed the new one quick so the oring wouldn't come disloged and fall some where(who knows) and evrything has been fine. My question is, has anyone else had the oring not come out with the rest of the fuel screw parts while installing the new screw? If not should I take it back out and see if I can get the oring to come out so I'm sure it's there?