... I have a couple that have warped that I need to do something about.
Paul; I carefully sanded down the thickness of bars you're talking about at the ends where they fit into the slots. That way they fit loose and will not warp. You could try removing yours and strightening them by ironing... seriously... I've done it before. Many quick passes with the parts under some cardstock so as not to melt the plastic and they should straighten out for ya
If you burn the cardstock you're going too slow
Mike