I wonder if there's room to put some pieces of sound-deadening material like Dynamite on the inner/upper face of the under tray? You don't need much to damp out vibrations.
Good idea to eradicate the problem but a little noisy Tim
2009 4/4 Sport Henrietta 1999 Indigo Blue +8 2009 4/4 Sport Green prev 1993 Con Green +8 prev