Volvo Repair: Volvo mirror replacement, old glass, turbo wagon

Question
I need to replace the glass of my exterior left mirror on my 1991 740 turbo wagon. I see a slot under the center of the body but don't know how to release the old glass and secure the new one. I'd appreciate your advice.

Answer
there is a white plastic piece in this slot that has 3 notches in it you pry this piece towards the car I believe but am not sure it may be the other direction.pry this white piece over just about the lenght of the slot and it should release the glass.