The old original lock cylinders have a bar that stops the barrel turning in the cylinder. If the key is worn this will prevent the bar from dropping and the cylinder will not turn. If your ignition key is the same as the door keys, and the door lock cylinders turns operate ok, you can go to the Ford dealer and purchase a replacement ignition lock cylinder and build it to match your existing keys.
It’s a simple operation that can be done in 15-20 minutes by yourself. It’s best to have 2 keys so you can test the operation of the cylinder with both keys before final assembly, as you can take a file to the tumblers to get a perfect match.
If the door locks are a little tricky or worn-out, you can build these sets as well.
If the key is pretty well worn out, and you want to replace all door locks, here is a good tip.
Take the last four digits of your chassis # (vin) to the dealer, tell him you need 2 (two) “S” PATS keys cut using the last 4 digits of your chassis #, this new key code will start with an “X” he/she can retrieve the entire 8 cut code from the book and cut you 2 complete keys.
You can then build 2 door lock cylinders and an ignition lock cylinder so all keys match. (Or if you want to delete the PATS, just cut non pats keys) so long as you follow the directions in the kits, you will have no problems building the cylinders.
Be advised: when building the lock sets be sure to use the grease supplied in the kit.
If you choose to retain the PATS, you will need to have the keys programmed.
The reason for using the last 4 digits of your chassis# is that the key cut code in the books only has 4 digits, for example something like X7652, this will help out if you need to have additional keys cut in the future.
I suppose you could also go the local Chinese parts vendor and buy a cheapo lock set that may work for a while. But trust me on this one, you can’t get a better built lock set than one built by your own hands.