I've had some great help from this forum in removing the centre air vents and the microfilter etc to try and find the missing vanes from the centre vent - thank you.

Unfortunately, removing the microfilters didn't find them because its the wrong side of the evaporator/heater core (not sure which one it was).

If anyone's had their ventilation system/heater assembly etc apart, where is the most likely place these loose small vent flaps and the little bar between them have ended up?
And is it accessible from somewhere relatively easy?

They don't rattle or anything, but I'm a bit worried they may block flaps or openings or the fans and I really don't like the idea of them being in there free to float around.