Chasing sources of vibration seems to be a never-ending problem in microscopy. Here are the approaches we've taken to two different sources of vibration affecting our Hitachi S-800 FESEM. One of the first problems was with a window air conditioning unit in the room that was needed to augment our so called central system. The existing window unit vibrated the window, walls, and floor. One solution may have been to buy a split unit so that the compressor was outdoors, but there was a moratorium on buying new air conditioning units