What about the other 6 million? think

Again, if manufacturers could be convinced that missing kit was a "real" problem (as in, one that created "extra value" - features - that they could charge a premium to solve), I'm sure that "technology" would pretty soon kick up the answer!

Off the top of my head, I think I would go for (what would effectively be) a cell-phone embedded inside the pump casing; just another small board. The person trying to locate the device sends out a "ping" (SMS, maybe), and the device silently responds. I believe the location of the reply can be traced in the same way that "texting drivers" can be nabbed. You know, a kind of "E.T. phone home" sort of thing! smile