@ken167 - Yes, four screws under the mirror glass. If you're trying to do this and you live in a place with salty winters, the screws will not be easy to deal with.

If you do manage to take your mirrors apart, make sure you try to clean as much corrosion off the bare aluminum frames inside as possible. One of mine started to split the plastic stalk the mirror sits on because it was puffing up with corrosion.