o/s/f door locking

Hi
right my osf door will not lock on the key fob will lock on key and door pin but not on remote

Once key is inserted into lock to lock or unlock the led doesn't flash should it flash or not?

I've found a door lock for sale but would like to be sure it is the lock that is at fault I understand that the osf door lock is the master

I've tried the keyfob registration but it didn't work so I'm assuming the microswitch is up the duff

What do you guys think

Many thanks

Dose the key fob lock/unlock any of the doors when pressed?

Hi forgot to say all other doors lock and unlock just drivers that won't on keyfob

All doors lock and unlock on key in barrel amd door pins

Many thanks

central locking motor burnt out then, but check the wire loome that runs along bottom of door as its prone to damp in the sockets and rusting.