Hi Leon,
Mine came loose, it was attached by only one of the original fixings.. (which was just about holding it in place).
I got some similar panel fixings from Hellfrauds,(the type with the cross head screws in) but the diameter was still to small..
I pushed the fixing into a cavity wall plug to increase diameter, eased into place then fixed in the cross head that came with it to push the whole thing tight...
It goes no where now!
To be honest, i wouldn't think this would cause the rattling you can hear...
I only noticed mine loose during routine maintenance.