Hi Freddy, Are these the overhead air vents you are talking about? If so, I went through this recently with my 252. Older but similar. Repairing them is fairly easy, but getting access to them is a huge PITA. Let’s talk about the easy part first. The butterfly valve is opened and closed by turning the outer ring of the nozzle which turns a ring clip that has a u-shaped tab with a slot in it. A little rod attached to the butterfly valve sits in this slot in the tab and as the ring clip turns in t