I'm a clumsy oaf. I dropped my 5Dii with 100L attached. The lens started making a repeated buzzing when attached to the 5D and my 7D. Other lenses don't buzz on either camera.
It's been back to Canon twice now, and both times they've said they can't replicate the fault, so can't repair it.
When it comes back this time I'm going to try mounting it on further cameras, but can anyone on this forum suggest anything that could be causing it to buzz for me and not Canon?