Rekey, repair or replace?
The answer starts with what you want to change. Who can unlock the door? How the lock works? Or the hardware itself? Those can sound like one job until you look a little closer.
Rekey when the concern is the existing key
Imagine the lock works smoothly, but you have just moved in and do not know who kept a copy. Suitable hardware may be rekeyed so a different key works. The handles and visible lock can often stay.
Making a copy is different. It adds another key with the same access. Rekeying changes which key operates the included locks. Any door left out of the job keeps its own arrangement.
Compatibility and condition matter. Several locks may be able to share one key, but not every mix of hardware permits it without changes. Count the doors first, including the entrance from the garage or a side gate you want considered.
Repair when something has stopped working properly
Now imagine the key turns easily with the door open but catches when it is closed. The bolt and frame may not be meeting as they should. Changing the key access alone would not necessarily change that behavior.
A loose handle, worn key, damaged cylinder or latch problem needs its own checks. Describe what happens rather than taking the lock apart to name the part. A spare key that behaves differently is a useful clue.
The proposed repair should connect to the symptom. Ask what has worn, what can remain and what will be tested afterward. Ordinary closing and locking are a better check than turning a key once with the door standing open.
Replace when the existing hardware is not the right starting point
Some locks are damaged, unsuitable for the desired use or simply no longer the hardware you want. Replacement can make sense, but it should follow that reason rather than an automatic rule that every lock problem needs a new set.
A smart lock is also a hardware choice. The door preparation, fit, exterior suitability and backup entry need checking for the chosen model. A motorized bolt should not be expected to overcome a door that already binds.
An exposed Manhattan Beach entrance may call for attention to the actual product's materials and care. A coastal label alone does not prove that one product is suitable or another has failed.
Sometimes the sensible plan has two parts
You may want an old key stopped and a sticking bolt repaired. That is a clear request for two results. Keep them separate in the discussion so the estimate identifies each part.
For a rental or common entrance, get permission from the person responsible before making changes. At handover, test every included door and key, and check which old access should no longer work.