My B's air vent flaps have lost their frictional stability - they have become very loose so close randomly when I need them open. Any ideas for improving their 'tightness' ?

You may find that one of the 'elbow' joints that operate the flaps have popped out. On the inside of the flaps, on either side are the two elbow joints, they are connected by small ball and socket joints, one of these can pop out resulting in the flaps being loose. Unless you have small fingers you will need to pull out the unit and from the other side just click the elbow joint back into place and the flap should be as good as new.
Regards
MarkII

Thank you Mark 11, I'll give it a shot. I presume the whole unit can be simply pulled out? Thanks again! - Dave

On the outer air vents, I think you will find a small mark on the inner rotating part and a second mark on the outer ring that looks like this, =, line them up and they should pull out. I have not taken off the central air vents, but it might be worthwhile checking to see if there are any line up marks, if not I presume they will just pull out as they look shallower than the outer vents, which are about three three inches long.

I have managed to find the air flap I took out, the air flap is basically a closed tube when you push the flap to open, the mechanism also pushes open the other end of the tube allowing the air in and closes both when the flaps are shut. The mechanism is more central then I remembered but are still these reciprocal push fit elbow joints. I will try and post some photos tomorrow.

The two pictures were taken from the back of the air flap and you can see the pin that can pop out, which attaches to the rear flap and also the bar that runs from front to back on which the pins are located.

Many thanks Mark 11 - indeed the outer vents have the locating marks. I had an hour in the traffic last week, and at one stage the sun shone directly onto the central vents. I studied them carefully and see that on the outermost part there are two tags into which a screwdriver has to be inserted, whereupon it looks as though the whole unit comes out. I will try and let you know if I get them out.