Rear door lock issue

[Alfa-mad]

To the resident experts, one of my rear door locks makes a buzzing noise when you lock and unlock it, and it doesn't appear to work consistently.

For istance, when the car is off, I can lock and unlock it no problem although it makes this loud buzzing sound.

But, if the car is on, I can lock it (or it locks automatically at 20kph as it should), however if I try to unlock it while the car is still on when you use the door lock/unlock button on the centre console, it won't unlock. I have to turn the car off for to be able to unlock it.

The loud buzzing sound led me to believe it was a physical issue related to the cogs, perhaps not meshing as they should anymore but when I pulled the lock apart, I can't see anything broken or worn down.

Does anyone have any idea why this lock is loudly buzzing and misbehaving?

EDIT: Thinking about it some more, since it still locks and unlocks while making the loud buzzing sound, perhaps its the little motor (circled in second photo) that is perhaps beginning to fail? Sure I could eliminate all of the guesswork by just buying a replacement lock but I want to avoid that if it's an easy fix. But then again, even if it is an easy fix, it still might not be worth it because it may fail again in 6 months or so.

Eager to hear what the experts here think

[Alfa-mad]

UPDATE: I found the source of the door lock issue, confirmed it was the little electric motor.

As I suspected, these electric motors are nothing unusual, I've seen these type before in toys and other things and figured they would be easy to source and sure enough I found an exact replacement for around $15.

So I sourced another motor, put it in place and tested door lock, its back to functioning normally now.

If anyone has door lock issues where it is making a loud buzzing or grinding sound when you lock/unlock and its playing up, let me know and I'll tell you how to fix.