Not quite the exact same issue you have as mine wouldn't unlock, rather than failing to lock, but otherwise sounds very similar to an issue I had. I just completely replaced it. It seems like a pretty sealed unit so I'm not sure how much luck you're likely to have trying to repair it.
Ended up taking mine to a garage to get it replaced as it's tucked behind the inner door skin which if I remember correctly is held on by a combination of bolts and rivets. I'm sure it's probably possible to replace yourself, I just didn't fancy drilling out rivets with no idea what else might be behind there
Door lock actuator
in 370z Technical
Posted
Not quite the exact same issue you have as mine wouldn't unlock, rather than failing to lock, but otherwise sounds very similar to an issue I had. I just completely replaced it. It seems like a pretty sealed unit so I'm not sure how much luck you're likely to have trying to repair it.
Ended up taking mine to a garage to get it replaced as it's tucked behind the inner door skin which if I remember correctly is held on by a combination of bolts and rivets. I'm sure it's probably possible to replace yourself, I just didn't fancy drilling out rivets with no idea what else might be behind there