Using common hand and power tools such as screwdrivers, saws, drills, wrenches, and hammers, as well as some specialized equipment and electronic testing devices, these workers replace or fix worn or broken parts, where necessary, or make adjustments to correct malfunctioning equipment and machines. They inspect, repair and maintain machines, mechanical equipment, buildings and work on plumbing,basic electrical repairs and upgrades, and heating, ventilation, and air-conditioning (HVAC) systems.