Learn how to properly install and adjust a Unity Spotlight. Never take it apart to see how it works, if you want to use it again. Most times that a spotlight is disassembled, it is usually not reassembled correctly, leading to problems that you can't solve, such as the handle switch not making the proper contact with the shaft. Think of the spotlight as a precision instrument that is properly adjusted at the factory, and to give continued satisfactory service, that it only be repaired by an experienced technician. If you want to learn how they work, then start off with one that is already broken, not a good working spotlight...