Corsa 1998 - Just under the LCD and above the heater controls etc, are the two air vents with hazard light switch inbetween. The air-direction-wheel in the left hand vent has moved away and is sitting loose inside. I removed the radio, the air-circulation slider etc and found two screws, still, the front panel won't come off. Now I read in newsgroups that the vents themselves can be removed with butter knives. Just tried, still can't get the damn thing off. Is there some knack to this?