Just got one of these today, and after getting it installed in the house, I'm having some trouble with the shelves. Since I'm putting my long guns in this one, I had to move the big shelf up a foot or two, and those little metal things that clip into the rails along the safe wall will not re-seat themselves. They keep popping loose before I can situate the shelf. Has anyone else had experience with these types of safes/shelves who could share some tips on how to get those little buggers in there?