Yesterday, I noticed that one side of my front bumper was loose.  After looking into it,  I can't figure out how you are supposed to tighten the large black allen key bolt that goes into the front of the bumper (the two facing forward on the left and right).  The left one is loose but the round non-hex nut thing inside of the bumper spins when I turn the allen nut.  Was this thing originally welded to the bumper mounts?  How else could you possibly get to it?  It's almost impossible to see let alone get to!  Am I missing something here?
TIA
Nat 
Seriously rainy Seattle