You could do worse than have a look at the back box. Mine still functions perfectly but seems to be made with layers of metal and one by one are starting to laminate, or seperate if you like. Every speed hump gives a slight thump from the rear, but you can peel the layers off a bit like an onion which cures it, at least for a few months, and then you can peel the next loose bit off.
I've been peeling them off for two or three years now and it's never done me any harm :devil: