It isn't too hard to pull the door handle and/or tailgate handle. The lock cores are each held into the handles with two m6 bolts. In the case of my 04, I had a few problems. The tailgate lock was corroded so bad it wouldn't turn, and the door lock/key was so worn that the tumblers weren't retracting all the way.
Once you get the locks out of the truck, it's pretty easy to inspect and disassemble, clean, rekey, and lube them.
1) Pop the e-clip off the back of the core and remove the lever.
2) Pry up the little crimps on the side to get the chrome cap off (the end where you insert the key)
3) Insert the key so you don't loose any tumblers or little springs and pull the core out
4) With the key firmly seated, inspect the core. You should see that the tumblers are flush with the body of the core. The whole assembly needs to be round to turn in the lock. If it isn't, it locks into the slot in the lock body.
5) If tumblers are sticking up slightly due to wear, they can be filed down by hand. I'd recommend removing them one at a time so they don't get mixed up. If they're sticking up a lot with the key inserted, you'll need to remove and reassemble them in a different order to make them match your key cuts. It's ok if not all of them go back in, but use as many as you can. The more you can use the better
6) Reassembly is reverse of removal. don't forget to crimp that little chrome cap back on in a couple spots.
7) By the way, it's best to lube locks with something that won't harden or draw dirt and grit. I usually use a bit of graphite.
I'm pretty sure I have a spare tailgate lock in my toolbox. If you want to try tackling this yourself, I could probably snap a few pictures so you can see what I'm talking about. There are a lot of small pieces, but it's not hard at all. I actually find it's kind of fun.
