This is a Zumo 550, about 18 months old. It's been used, but not abused. Been down it's share of bumpy dirt roads, but it's somewhat isolated from vibrations by a RAM mount. Anyhow, I picked it up yesterday and noticed ... it rattles. And not like a tiny screw came out, but like there is a decent-sized something inside that came loose. GRRR. Before I start taking it apart, I was wondering if anyone else has had this happen. Or if anyone has any caveats about dissecting these things. I've got to say: I'm not impressed with the Zumo's durability. Its car cradle kicked the bucket a while ago -- it simply stopped charging the unit. Just recently my bike cradle started acting up, also not connecting well enough with the Zumo to charge it. A bit of dielectric grease on the connector pads normally solves this, but still .... Not cool. And now this. Meanwhile, my wife's old 276C is still going strong. Stupid new technology.