Rattle in the glovebox

I have had a rattle noise coming from my glovebox for some time now (Over 1 year). It doesn't rattle when open but only when closed and driving. I tried to show it to the dealer but perhaps the roads around the dealership were smoother because after much testing, they were able to hear the rattle A LITTLE. They placed 2 small pieces of rubber or plastic on the inside of the glovebox towards the top right and top left sides. It still rattles. When I brought the car back to the dealer for this they couldn't find the problem. It is not a major issue because it doesn't have anything to do with the operation of the car BUT I would like to have it fixed. Do you have any suggestions on how to show this problem to the dealer so that they can detect and fix it?