Everyday locks, such as those found on office mailboxes and cabinets, get a lot of use. The more use a lock gets, the more important it is to have that lock functioning properly. Changing the locks on a mailbox or cabinet is similar to changing the lock on a door, with a few important differences. The largest difference is usually in the mechanics of the lock. Where a door lock usually retracts a bolt to open, the plug of the key in most mailboxes and cabinets is fixed to a bar that rotates with the key turn.
The first step in replacing the lock is to open the locked mailbox or cabinet. For a standard office mailbox there may be an additional key that is held by the manager. If the key has broken in the lock, or is missing, the lock can still be opened (see about business/office lockout above). There will be a pin on the lock either turned facing up or to the side.
This pin is removed, most often by hand (there may be a nut that needs to be unfastened), and the lock can be removed from the hole. The new lock is then inserted into the hole and a new pin is placed to keep the lock secure. If the bar that is bolted to the lock is too long to be slid in with the lock, it may need to be unfastened. Once the plug of lock is secured to the bar and the pin (or secondary nut) is replaced, the lock is ready for use.