Thanks for the messages and the help. I'll certainly try the recommended "fixes". Having read all the threads and comments, the rattle in my car is worse when it's hot outside (most of the time in Cyprus!) not when it's cold as suggested in some of the responses. There is no rubber stopper adjacent to the top lock Mechanism so maybe that's it. I have tried shaking the lid when it's closed but it seems really well fitted and secure. I'll keep you posted on my progress.