I had the fortune and pleasure to talk to a few TGL designers at one time, and was told that TLG themselves use an "oven test" to test model design. This means that they heat all models to 60-70 degrees for many hours. Excessive heat makes the plastic shrink a tiny amount. They do this oven-test to verify how well a model will hold together when being played by kids (i.e. a way to identify weak spots in the design). In other words, excessive heat will make the pieces loose their clutch power because of plastic shrinkage. I had a talk to a professor of Polymer Materials some time ago, and he said that part of the explanation is the butadien (rubber) componentn in ABS that will make bricks shrink ever so slightly. Compare to an old rubber band and see how it becomes brittle and dry over time. Of couse this process is much, much slower in ABS then in rubber; but it occurs to some extent. So in SuperCurrys case, it may have been that the Lego had been exposed to high temperatures of a longer period of time. Perhaps the LEGO was left in the trunk of a car or similar for days? Then there is another intresting aging process in Lego bricks that is worth mentioning, and that is INCREASED clutch power due to increaseed surface friction. This is caused by molecular changes in the surface structure over time. At TLG they have huge shelfs with drawers of Lego-bricks used by designers to build models. This Lego is replaced every 5 years or so because the clutch power increases over years - older brickcs become more "squeaqy" when put together. And once again, designers do not want Lego bricks that hold together in a way that is not representative of how the bricks act out of the box. However, heating bricks in the "oven test" will make them shrink more than the friction increases. Hope that helpes somewhat. Naturally there may be other causes for shrinkes, for example if the Lego was exposed to various chemical agents, but the first thing that comes to mind is the heat. Trivia - regarding the oven test, TGL ran in to troubles when they wanted to test the UCS Millenium Falcon. Their test oven was simply to small. So they called a local Pizza-place and borrowed their oven. Funny but true