I've had many locks apart - esopecially Rover ones and they all suffer from water ingress. This affects the internals and makes them stick. The toggles have the most miniscule amount of lubricant on them - therefore after a few years the lubricant is just about useless. WD40 is a great way to lubricate lock internals - however you will need to do it on a regular basis (WD40 will also stop your satellite picture going off in heavy rain - just spray the dish head and its fixed!!).

Locks can be dismantled if you take your time - wash the internals in parafin or clean with surgical spirit (I prefer). lubricate with vaseline and reassemble.

A bit of advise when its frosty - clench your fist loosely - put it against the door lock and blow hard for 10 seconds - this will defrost the most frozen lock!!! It's NEVER failed in my 40+ years of motoring.

Hope this helps

Robin the Technician - I fix, therefore I am

I bought a 406 hdi estate as a stop-gap car. BAD MISTAKE! Good points are that it uses no oil or water. Bad points are locks and fob. When the car was purchased the seller said that he just used the fob as the metal key would not open the doors (note by fob I mean the fob built into the key)

The car had been working OK the day before but in the morning the car would not open. The red LED on the key was not lighting indicating a dud coin cell. When a new coin cell was fitted the LED lit-up all the time! The button, which is rubber, had swelled-up and presumably the fob had been generating codes all night long. Fob and car now out of sync.

To re-sync one has to disconnect the car battery but the bonnet release is inside the car. The Pug dealers advised smashing a window. Instead WD40 was tried on the locks. The boot lock almost works but it fails to catch properly. Possibility number 1 is that the car has Superlocking. Possibility no 2 is that the ignition lock and key have been swapped by by a previous owner. Its likely to cost a packet to put right.

Some drilling might be next.

This lock spinning without engaging used to happen regularly on Citroen C5 even brand new (in transport mode remote not connected), nine times out of ten a bit of wiggling and it would open, probably similar internals of the 406 of those years.

Regular greasing of the locks is something i have always done, especially on cars with remote plippers where invariably the boot key lock (if the maker was sensible or generous enough to fit one) would have never been used and would often be almost seized.

I use chain lube or spray grease via an aerosol with extension probe, shove the thing right into the lock and give it a blast, best done now before the first winter salt and flat battery combine to give you a right headache one morning.

One thing i love about Landcruisers, central locking as well as via plipper also works via the keyhole from all three door locks, very handy when the oddly poor Toyota plipper breaks apart (the locks themselves are high quality products so why supply a cheap rubbish key on such a vehicle), as FB above, plenty of spare casings with blank key on the bay so quick changeover of innards and get a locksmith to copy the old key, job done, £15 by the time its cut including a now flip open plipper versus getting on for £200 for a new basic plipper from the parts desk.