Here are my notes and photos from pulling the driver's side vent in order to pop the fins and slider back into place. Start by pulling the unit as is described elsewhere, as if you are accessing the headlamp switch. I went ahead and disconnected everything so I could wrestle with opening it up. The only difficult part is in separating the internals from the housing. There are four tabs that hold it together and mine were a real bear to get apart. One side was no problem, the other was tricky and hard to get the tabs to budge. In the end, I think it was more force than anything that got it apart. Once that's done, the rest is easy. The horizontal fins are even numbered so you know the order they sit. The vertical slider simply snaps into each fin.
Yellow arrow shows vertical slider. Green arrows show tabs.
This is what popped out of place, along with a couple of horizontal fins.
In this photo, yellow arrows show the 4 tabs.
Detail of the tabs. They are not very flexible, hence the problem popping them out.
Side view of body.
Showing the fins that had popped out.
