Sticking FD central locking - cause?

[lockwood77]

I need to get the central locking working properly on my FD, so the new owner is happy.

It seems to be the driver\'s door that\'s playing up - I can lock with a key, but just using the remote doesn\'t work. Once the door is locked, it can\'t be unlocked with a key or remotely - you have to unlock the passenger door and lean across to flip the lock up.

Anyone know what the likely cause is? Obviously I\'ll be getting the door card off, but it would be useful to know what parts I might need (if any).