I think it's common that over time the dash deforms around the vents, especially in hot climate. My car is original from Florida, and the dash had deformed to such an degree, that the actual vent. fall right through the hole.
I did cut out a litle of the form between front dash and backside, made a small frame around the vent., pressed it all back into the dash, and secured it from the backside with some Sika-flex 221.
I think it's almost invisible, but see for your self.


