The mirrors snap on, with two spring clips and a keyhole clip on the back (hidden) side. Loose mirrors could be caused by bent spring clips, a broken keyhole clip, or merely a spring latch that has popped loose. The first thing to do is just try to snap the mirror back in place. The spring clips are located at the center front of the mirror and the rear bottom. If the front is where it is loose, rap sharply with your hand on the back outer corner of the mirror to try to snap it back in place. For the bottom being loose, you would rap downward from the top outer edge. Ifv the top rear is loose, you have a broken keyhole clip that will need to be replaced.
If you can't snap the mirror back in place, the spring clips are probably bent. Remove the mirror by rapping on the outer edge sharply while supporting (and resisting) the mirror with your other hand in the opposite direction. I rap backward first, to release the front clip, then upward to release the bottom. Be careful not to go too far or pull outward, lest you break the keyhole clip. When the front and bottom/rear clips have released, slide the mirror straight upward about 1/2" to release the keyhole clip, then pull the mirror outward. You can disconnect the wires at this time if you wish.
You will see two spring clips, which have a pair of spring wires each. carefully straighten the wires so they are straight and parallel. Put a little lubricant on the cone parts of the latch posts. The connect the wires, slide the mirror on the keyhole clip, then rap sharply downward, then sharplty forward to snap the spring clips in place.
