Lucian84

The motors and gears in the flap actuator are usually durable, the one that fails often is the position potentiometer, it needs cleaning with special potentiometer spray. Fixed mine, now it works like new, search on google there's a tutorial with pictures for this.

Change the mirror glass, it's cheap and easy to do. Also clean the contacts and spray them with a contact cleaner. The heating resistances for left and right mirrors are equal (100 ohms as i remember) so they must perform the same way.