I was lucky with the con cor sets. It hadn't happened to those, because I got them from a big collector that kept them in a climate controlled room. I have first hand seen it with other sets though. It was mostly a Con Cor thing, but not entirely. I lost an $800 Brass steam locomotive due to that though. It was from the same era, and was using the same foam Con Cor used in the box. I was in storage for years, and when I opened it up (I bought it in a "lot" from another collector) it was just the loco flopping around in a box full of sticky goo and crumbs. The foam completle decomposed, and ruined the finish on the loco, as well as gummed up the inner works, from even getting in there.