I was at my Dealer the other day, And I Guy came in with his F 7 and the skid frame and the tunnel were bent right up, He said he was flying down the trail and it just locked up and threw him off it, When he look at his sled it was bent upword it turned out his slide rail end cap cam off and got stuck in the track and loocked it up, Now This might be Just with his sled, But it cant hurt to check them, I had one that was not really loose but was not real tight. It only takes a sec to check.