Both of mine have been weak since I got the car, the passenger side needed help to lock and unlock so today I took it apart to see what I could do. The actuator is pop riveted in unless it's been replaced already, in my case I had to drill them out. When you reinstall it you can use 1/4X1/2 inch bolts and nuts. Once they're drilled out rotate the assembly up to get the linkage rod out. I had a nice clean eBay motor with an intact seal ready to install in place of my old one, and after a little wrestling getting the linkage rod in I discovered that the new one would only work intermittently so I took it back out and took it apart. The actuator has 3 or 4 screws that go through the bracket into the motor, I took these out and pried the motor housing loose:



Once the housing is loose you can carefully lift it free from the actuator housing, being careful to lift the motor straight up so as not to lose the brushes and springs which sit in the actuator:



Once the motor is off the actuator you can pull the armature out of the motor housing and on the tip you will likely see a plastic bushing. In this one the bushing is apparently copper or brass and is embedded in the bottom of the motor housing. Either that or else the bushing has melted itself into the housing from lack of lubrication:



So once you've got the armature out you can clean out the housing, it's likely to have old dried up grease in it that isn't lubricating anymore and is slowing down the motor and actuator. Once it's clean you can put a dab of grease (I used lithium grease), either on the plastic bushing at the end of the armature or in the bottom of the motor housing. Bear in mind that if you use a metal brush or metal anything to dab grease into the motor housing, you'll discover that it's lined with very strong magnets that make it nearly impossible to center the brush. Before you put it back together push the actuator rod in and out of the housing, it should be smooth and no hangups, I sprayed a little graphite lube in there. Now you're ready to reassemble, first push the narrow slotted end of the armature into the actuator and turn it until it drops all the way into the housing. At this point it will be sitting on top of the brushes:



Now for the tricky part, you have to install the motor housing onto the actuator without pulling the armature (and possibly the brushes and springs) out of the actuator housing. Remember that the motor housing has powerful magnets embedded into it, so you'll need exert a little pressure on the side of the armature with the housing as you push it on in order to keep from pulling it out. Push down and to the side until you encounter resistance and the housing stays in place, it will look like this:



Now you only have to push the machine screws through the bracket and actuator housing and tighten them until the motor is sitting flush with the housing. After you've done this plug it in and verify that it works, in my case I had to reinstall the armature because I'd pulled one of the brushes loose on my first attempt. If it works then you can put your door back together. One thing to bear in mind is that the rubber seal on the linkage end of the actuator housing is often deteriorated and doesn't keep water out of the actuator housing, especially because that end is installed at an up angle allowing water to easily get in. If your door seals are good maybe water doesn't get in, but it's something I noticed. After doing this procedure on mine the passenger door locks and unlocks with plenty of power, tomorrow I'm going to do the driver's door.