Maintenance and repair workers often do work that involves electrical, plumbing, heating, and air-conditioning systems or painting and roofing tasks. Workers need a good working knowledge of many repair and maintenance tasks.eneral maintenance and repair workers typically do the following: 1  Maintain and repair machines, mechanical equipment, and buildings. 2  Troubleshoot and fix faulty electrical switches. 3  Inspect and diagnose problems and figure out the best way to correct them.