You answered your own question Dave.Your door locks need a lube.Go ahead to your local "Pep-boys" and get the "STP" siliscone-based lubricant, it comes in a blue spray can, it states that it outlasts "WD 40", and in my opinion, it certainly does.Spray a good amount of it on the ouside lock where you insert the key, also on the inside mechanism(got to remove the interior panel, not so hard to do), play with it up n' down a couple of times and there you go.