The motor assembly could possibly be loose. You know, like a little play in the motion of the motor. Anyways, to take the glass off, you can basically just pop it off by using a long screw driver and prying it off of the motor base.
And as far as the LED mirror install... if your patient, it'll go fine. All depends on how you chose to wire them up, and how much concern you have with hiding the wiring. I'm not patient, and I don't like visible wires, so my install looks like the car came that way.