UK Ford Escort door lock problem...

Bit of a peculiar one maybe.
The drivers door on my 94 Escort is a right buggar to unlock with the slightly worn black keys. With the Red master key it's a breeze to
open. I even had a new key cut from the master, and it's still very tough to get it to unlock.
All the keys, master and the 'slave' keys work perfectly in other doors and the ignition. It seems to point to a combination of worn lock and worn keys playing havoc with the most used lock on the car.
What is the best course of action for me to take? As I said I've had a new key cut to little avail. Do I need to get Ford to look at it, or is there something I can do myself?
Cheers.
Strutter
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strutter snipped-for-privacy@hotmail.com wrote:

FIRST step is to spray in a lock lubricant.
Second is to either have it replaced with the same keying or swap it with a lesser used tumbler
--
Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price
you pay..DEAL with it!
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