[kidrock]

I'm finding out that the original keys are getting pretty worn down on our cars, and sometimes will not actuate the glove box lock tumblers properly.

I would use some WD-40 (Tri-Flo is better) and gently manipulate the good key you have left. Work the key up and down (or in and out) gently to try to get the tumbler to unlock. It may take several minutes, so be patient.

If this doesn't work and you run out of patience, you can take a pair of pliers and twist the lock face to the left or right until it frees itself from the catch. Of course, you will probably ruin the lock face and need to purchase a replacement after doing this.