Lock issue

[MEL744]

Hi all,

So the other day I noticed my 06 Jetta's passenger door was not locking, while all the other doors were. Today I began to take the door apart to get to the lock, however before I did this I noticed a plug on the end of the door. Underneath the plug there was a red switch/lever, and when I push it inwards the lock works as it should for a few locks/unlocks before no longer locking. Also, when the lock button is pushed on the remote a noise can be heard in the door, even though the door doesn't lock. These two things make me think the lock isn't totally cooked, but could be wrong. Any help would be appreciated

Cheers,
Michael