Got a new universal door lock acuator off Ebay for under $10.00 with free shipping (showed as compatible with 2000 Mazda Protege). Not only was it easy to install, it works better than the OEM. Not counting the removal of the door panel etc., it took me 5 minutes to install the universal replacement. That new actuator (which is twice the size of the OEM and has a different design) really slams the door lock up and down like it means business! Now the back lock works too because the front passenger side (the one I replaced) was apparently draining the circuit because it was worn out and the rear one was not getting enough juice to work all the time.

The install: Remove the old actuator (two small screws) and unplug the harness. Cut the old connection off the old actuator as you will re-use the connector. Connect the old connector to the wires of the new actuator by pushing the wires into the middle of the new plugs and crimping tight with pliars. There is no issue of which is positive and which is negative because that does not apply. Wrap with electrical tape. Using one of the holes already in the door (seriously, as if it was made for it) visible on the outside of the frame (I mean in your face!), attach the flat steel piece to the steel door frame. I didn't use the flat piece because the actuator fit perfect to the door frame without it, but it is up to you. Make sure the actuator and related do not interfere with other parts of the door, it should not. If you need to bend things a little, that's OK but be careful. Now connect the actuator to the flat metal piece (if you used it) using the holes and screws making sure the actuator motor does not interfere with anything. No modification required but if you want to drill new holes in the door frame and use the metal screws that's fine. Using the supplied rod and hardware, attach the supplied rod to the actuator (L shaped with a ball at the end goes through the hole on the top of the actuator), then use the special adapter to attach the new rod to the rod that has the door lock on the end. The end of the new actuator rod pushes through a hole in the middle of the adapter and it slides for adjustment. Both the actuator rod and on the door lock rod will slide in the adapter for adjustment until you tighten themn up. Push the door lock to up position, then slide the actuator rod until the actuator (boot will extend) is also in the up position. Tighten the three screws on the adapter (two for the door lock rod, and one for the actuator rod). The supplied adapter has a slot that lets you insert the door lock rod into the adapter then secure with screws. Connect the old connector you put on the new motor to the door connector. You're done. I should have taken pics but I was in a hurry to do the job. You will understand when you see the insides of the door etc.

As far as I can tell, the universal actuator design is way superior to the whimpy and fragile OEM actuators. It is a hoss! Time will tell if it holds up but it looks solid. Slam! Open. Slam! Shut. Great sound.