A friend of mine, working on his PhD in a European university which shall not be named, is using a really old 15 watt ruby laser for some experiments. One day last year it would not turn on, and he and his labmates spent hours trying to diagnose the problem. Finally one of them, exasperated, put his elbow on top of the laser cabinet with a deep sigh, whereupon the laser promptly started working. Excited, they found a big piece of steel and duct-taped it to the top of the cabinet in that very place, with a big "DO NOT MOVE"-note, and the laser has been working fine ever since.