Turn off the circuit to the metal junction box at the main service panel. Untwist any wire connectors from wires inside the box. During World Wars I & II, manufacturers used inferior aluminum metals for bus bars. Replacing an old junction box can be a daunting task, but with the right tools and instructions, you can do it safely and efficiently. Here's a simple, user-friendly guide to help you through the process. There's any amount of information about installing boxes of this sort, you just push it through the hole, tighten the two screws in the corners, a couple of wings pop up and clamp the box to the panel. These older boxes, frequently found in homes built before the 1950s or 1960s, present unique challenges compared to contemporary installations.