Might be this is a one piece assembly. Or someone glued the mirrow to the plate. That's unlikely if it hasn't been repaired before. Skip the dealer. These are industrial grade adheasives so the chemicals to insure a good repair are only available to the pros. Not to mention "Additives" ie; winshield curve, mulitlayer glass compounds, factory tints and coatings, sunscreen, you get the idea. Find a auto glass shop. Might cost as much as $20 bucks to fix. Well worth it.
