Passenger side mirror

Has anyone ever had to replace the glass on the passenger side mirror?
(2000 SL1, power mirrors)
My mirror fell off. It was only held on with two pieces of double sided tape. Bought a new mirror with backing plate from the dealer (~$45.00).
I got the old backing plate off ok, just appears to be a snap fit. I just can't seem to get the new one to snap in place.

If anyone has any suggestions (besides have the dealer do it)...

if its like my 94, make sure that little cross didn't brake.

I got the mirror on. There is a circular post in the middle and the backing plate has to snap onto that post. I had to push REAL hard from the middle of the mirror. I was afraid I was going to break the mirror. The backing plate also has two little posts that swivel, those connect to the actuators, so you have to get everything lined up for it to go together.