All interesting info, thanks for the replies.
My problem (similar to yours RonnyB): I've always had trouble getting the key to turn in the lock (both drivers and passengers side, actually). A few days ago the key became stuck in one of the locks. I was able to get it out, but now it doesn't work in that lock at all and the cylinder (probably not the name for it, mechanism maybe) seems loose. I'm afraid the same will happen to the other side and thought that replacing with new locks would be the best thing to do. Sounds like I might need to go to a locksmith...
