Air vent tabs

They are saying that because they can see the outer one working but the inner one not. I would say that if it was brute force then both vents would cease to work as there is very delicate linkage on both sets of move able items. I call the outer ones slats and inner ones vanes as a means of identifying them. I suggest that seeing as the vanes are operated by a hinged piece of plastic attached to the operating tab, that's more likely that the hinge was stiff and the prongs failed to flex properly ao the prongs caught on the vane instead of the bar. Look at my earlier posting for photos showing how this could happen. The whole vent is over engineered and this is common fault. I had 3 of my vents where the inner vanes were not working but I managed to fix them.