I've been driving around with the heater on high at full blast lately (getting a little chilly here in the Pacific NW), and after some spirited driving over some not-so-perfect road surface, the center vents then came loose. Eventually the whole thing come off in my hands when I gave it a little jiggle. I snapped it back in but only to have it come loose again. This only happens when the heater is on high and at a fan speed of 2 or above with all the air flow directed through the dash vents(not including windshield defrost). I examined the area and decided that this is something I could fix myself, but I like to know if anyone else had this happened to them and perhaps share some notes. This is a 19 months old '99 2.3 with less than 12,000 miles.