I've just received a used Bronica G-36 extension tube in the mail today. The item looks great physically but when I shake it, I hear some tinkering sounds like there's a million loose parts inside. I've never touched an extension tube before so I'd like to ask if this is normal or if something might be broken inside. Anyone thinks that is something that could interfere with normal use (especially considering that there's no glass involved in the product anyway)? I can't test it right now but I do plan to test it once I get back home to my GS-1.