If any of you, like me, have this problem and found this post via google - your screw is stripped out and/or missing - I went to Ace, picked up an M4 x 40mm bolt and nylon lock washer. Took a little bit of work to get it in since the stock threads were still SLIGHTLY intact, but I do mean "a little bit of work." Less than a five minute job and it's held under a few WOT runs in hundred degree heat and is definitely a better seal. Total cost was $1.79.