Thanks for your advice, Gilly. I'll try what you suggest. Just didn't fancy the airbag doing a number on me while I poked, prodded and pulled!
I did back off the bumpers (forgot to say that in my post) but it didn't stop the rattle.
Could you also please help me with this?... the top of the lid out of line with the the adjacent dash, very slightly, but I notice it. Is there an adjustment point or is packing used to do cure this? (I haven't yet removed the assembly).