Sorry I read your post wrong and thought you said the steel had side to side movement. What could have happened was whoever fixed your rivets initially could have stretched the holes where the rivet goes in when removing the old rivets (it happens) which is why you can move it side to side but it's still snug in terms of not having a gap and falling out. The only real way to fix the stretched holes is to remove the holders fill them with epoxy and re drill the holes. I would bring it back to the shop that did it to see what they say. I'm only guessing from your description