when soldering irons go bad

Tony Duell wrote: A friend recently told me about one of his friends buying a high-end Japanese-made electron microscope from Signetics as surplus many years ago. It didn't work, so he helped his friend fix it. There was a potted high-voltage power supply that wasn't working, and based on the symptoms he came up with a hypothesis that the module was internally miswired. They spent a lot of time depotting the module, and sure enough, it was miswired exactly as he predicted. They fixed that, and it worked perfectly. Apparently at some later date they went back to Signetics surplus, and the people there were very surprised, and perhaps somewhat upset, to hear that it had been repaired, and how trivial the fault was. They scrapped it because they'd never been able to get it to work!