[bigd1180]

1st You could have a weak spring so it wont lock in place. Get a repair manual it should have a diagram of this and the spring inside
2nd Take the 2 nuts behind fender off and top piece will come off making this repair easier. Go to a auto parts store and pick up some JB weld and some 80 grit sand paper and thinner. Sand the crack real good then clean with thinner. Apply the weld between crack. You will have to find a way to hold the 2 pieces together for at least a half hour if you get the quick weld and longer for regular weld. After that is set try and sand behind crack on inside of bumper, sand, clean with thinner and put on a good coat on crack. You should be good to go until you hit something agian!!! LOL