Ok, I ended up spending $15 on a power lock servo from the junkyard on Wednesday, and when I tried to install it today, I realized that it's not quite the same as the old one. Everything was identical except for the push-rod that moves the lock mechanism--the new one was about ½" too long. So I tore apart the old servo to see if I could somehow exchange push-rods, but they were riveted on. I found the problem with my old servo, though--a small copper contact rod had broken, something I could probably have fixed with a paper clip and some solder. Instead, I ended up removing the contact from the new servo and soldering it into the old one. I also exchanged some other parts, such as some gears and a little copper switch plate thingie, because they were in better shape. So what should have taken me less than 15 minutes ended up taking me almost two hours. It was worth it though, because having one door lock not work was driving me crazy.