[AU Fairlane S1] Remote Lock Problem

I bought this 2000 AU Fairlane V8 from the original owner who had it parked up for a while, as expected for an old Ford there are a few issues. One of which being the remote locking, I've been doing it oldschool and using the ignition key in the door to lock/unlock. I'm dailying this at the moment so it is starting to get annoying knowing it has remote locking, yet doesn't work.

I changed the fob battery and did the relearn procedure, now when I hold the button, the indicators flash and then the horn beeps a few times in quick succession. Also worth noting the central locking button on the dash doesn't effect the drivers door, which is the only door with a physical door lock. I am assuming there is a broken gear or cable or something that doesn't operate the drivers door anymore and the key fob sends a signal to the drivers door which can't lock and then doesn't result in anything locking.

If anyone has experience with the same or similar problem, any advice is much appreciated!