Mailbox Lock Replacement: getting ready

You've just moved in, and the mailbox compartment in the lobby came with a single key the previous owner mailed back separately, or never handed over at all. As far as anyone can tell, the lock still answers to a stranger's key.

Worth answering before the call

Is anyone else expecting to use this mailbox after the visit? Has a property manager or superintendent been told about this request? Is this a residential mailbox or a business mail slot?

Does road salt or winter weather affect these small locks?

It does. Outdoor cam locks sit exposed to spray, salt, and repeated freezing all winter, which corrodes the small internal parts faster than indoor hardware and can leave a keyway gritty or a cylinder stiff well before it actually fails. Whatever lubricant that cylinder's own maker specifies, used once or twice a year, helps a replacement lock last through more winters.

What causes a mailbox lock to wear out or start spinning?

Thousands of turns over the years wear down the small parts inside a cam lock the same way any cylinder wears, and a worn key accelerates it further. A cylinder that spins without engaging the cam usually means the connection between the two has failed, often from corrosion or metal fatigue rather than anything the resident did. Once that connection goes, replacement is simpler than trying to repair the worn parts individually.