Having intmt problems with the air conditioner flap on my 2007 Durango sticking and putting all the air to the floor vents instead of sending it thru the dash vents. Had the dealership check it out, but they couldn't find a problem...said that they lubed the flap. Has anyone else had this problem and how hard would it be for me to try to check if the flap is sticking? Thanks for any thoughts you have!