A friend of mine is replacing the mirror insert from his remote mirror on a 69 Dart. Someone told me that they had to break the mirror insert because the adhesive is strong. Any advice on how the easily remove the mirror insert (including tooling)? I'm assuming that one should tape up the chrome around the insert and place a towel on the door to prevent chips/scratches.

Thank you in advance for your feedback!

there are a few methods that i have heard of

one is to get a wet towel and wrap it around the mirror head
and heat the mirror up with a heat gun, moving the gun around
so the mirror heats up evenly which will make the adhesive let go.
i'm at 50% with that method as i got one off and broke another one.

another method i haven't tried is to put it in a pot of water and
heat it up until boiling and that should get it hot enough to do the trick.
that is what i'm trying out next time.

the easy way is to break it and if i wasn't trying to save it
that is what i would do.

I did my mirror several years ago and what I did was just to submerge it in a bowl of lacquer thinner - after about 24 hours the mirror just fell away from the adhesive. My mirror was chrome. If you have a painted mirror then your options are limited. My mirror was loose so after I tightened up the pivot I used some construction adhesive to bond the mirror back in place.

Same here. I removed the glass from a '72 vette mirror by submerging it in a bowl of lacquer thinner over night. Made the needed repairs internally and reglued it back in place with silicone.