First, make sure the mirror spring wires are straight and parallel. If they are bent inward they may not catch the post,
and if they diverge or bend outward, the mirror will be loose. It can help to put a very tiny bit of lube on the outer,
conical part of the post only. I'm talking about a film here, not a glob. Make sure there is none on the back side (post notch).
Engage the keyhole slot first. Then rap downward firmly (but politely) on the outer edge of the mirror to seat the bottom latch.
Now rap forward on the outer edge of the mirror to seat the front latch. You can rap a little harder than you can taking the
mirrors off, because they won't fly across the room, but don't get carried away. Problems seating the latches are usually
caused by bent spring wires.