If I could find an exploded view of that mirror it would be helpful but no luck yet. Tool wise, It really depends on what you have and what you want to do.
For me I would remove the mirror, strip it down, use a few trim and ding hammers and dollies and form the trim piece back to original shape. But unless you have all those tools already a replacement mirror is cheaper.
So use pliers with a rag on the jaws to twist the piece, a hammer to tap it back, basically use what you have.
A backer is simply something placed behind the part you intend to hammer on. It helps absorb the blow and holds the part in place so you are not just bouncing off. The picture shows how a backer works. In this case it is a real body dolly, but a piece of wood with a towel over it would work.
Sunday, January 1st, 2017 AT 8:37 AM