I decided, to save my sanity, to remove the trims for the time being to see what the problem was and whilst I found a fix.
Upon removing the trims, it was immediately evident time and condition changes had taken their toll on the plastic fixings that hold the trims in place. They had completely discoloured and every one had cracked or split. The one at the inboard edge had completely fell to pieces, and just fell out when I took the trim off.
I called up BMW and got 5 replacement fixings sent out, only cost 44p each which was a bonus.
Offering up the trim fixings against the old ones, it was clear just how aged the old ones were.
It took a bit of fiddling to work out how to get these fixings out, turns out they require a quarter turn clockwise then a firm pull upwards at an angle. And the opposite to fit the new ones.
Once all five fixings were replaced I refitted both trim panels and all was good as new. The new fixings hold the trims extremely solidly, and thankfully no sanity testing rattles.
