Having discovered the smashed tool tray and dealt with the damage with glass fibre, I found that in actual fact the tray was the wrong way round and had always been that way! But on rotating it 180 realised it would not fit that way as one of the depressions butted up against the rear. Rather than replace it the wrong way I trimmed the now front edge. With the rubber mat glued to the bottom of the plywood and a strip of wood screwed to the top of the wood bulkhead to match the new depth it all fits nicely and is sound and rattle proof!