IMO - Pull the door apart once. You don't really use the mirror adjustment that much to worry about a failure of a 'knock off', and some of the plastic pins on the interior body panels can break easily the more you fiddle with them.
Also, please add your year and trim of your vehicle to your signature line. That way when you start asking questions in other areas of the forum, we all have a better idea on how to assist you. Click on "Quick Links" above, go down to "User Control Panel" and then click on "Edit your Signature" It'* pretty straight forward from there.