If you need a new lock, contact the post office. Individual mailbox locks are an owner responsibility. According to CMS, the Postal Service has an entire maintenance division devoted to lock repairs. Arbors residents have complained that when they have contacted the local post office, they have been told that the post office does not do this, and to contact management. Reportedly, you have to show up in person at the post office, and the Postmaster will fill out a work order for the lock replacement.
Before replacing the locks of these mailboxes first ask a locksmith to check whether these locks need replacement or not. After their signal, you must go for doing the replacement. Otherwise, Call a locksmith to repair these locks.
Complaints regarding mailbox locks are increasing day by day, i recently seen a car locksmith came to my friends home to repair its car lock but he asked locksmith to repair its mailbox also. As the locks installed with mailboxes are not of good quality. That's the reason complaints are increasing.