Ok, yes I had looked at Kent's video but really wanted a puller that went all around the Pulley collar, but I did get it off and here are some items on the rebuild. First, as everyone says you can try to get the pulley off 1) taking the nut off (use an impact wrench) put the nut back on til the nut and shaft are at the same height, then sharply stike the shaft with a large hammer. It might come off but I would not try this for too long. If you hit the shaft wrong it can mess the threads up or bend it. So get a small two jaw gear or bearing puller (the steering pulley pullers the auto places "rent" out won't work, the collar they have are too small for a mercedes.) Your two jaw puller should have something to hold the two arms together. If not use a hose clamp. The reason you do this is the pulley arms to not have much to grab onto and by holding the arms together you have a better chance of them not flying apart. Once you have the arms in place simply start exerting some tension on the puller. When you have a bit, then hit the end of the puller shaft sharply with a hammer. Do this a couple of times. If the pulley does not pop off, then increase the puller tension, and hit it again. Keep doing this until it comes off.
Now for the rest of the story. I do not agree with only replacing the seal in the front. The extra parts to do a whole rebuild is something like an extra $3.00 so here you go.
1) After the pulley is off, take a pair of vice grips and remove the woodruff key. Clamp on the key with the vicegrips and just tap on the pliers with a hammer away from the shaft. The key will come out
2) YOu need a large vice or C clamp. 8" C clamp mouth or more. Get a large socket that will fit over the shaft and rest against the casing. Take your C clamp and with the socket on one side, and the back of the power steering pump on the other, put a little pressure on the back plate. On the back of the pump you will see a plate held in with a retaining ring. You should be able to put enough pressure on the C clamp to see the back plate move in a little. This will take the tension off the retaining ring and you should see a little play
3) With a pick, sharp screwdriver or whatever else you might think will work start to pick of the retainer until you get an end to start coming out. Once you do that simple keep walking it out by going around the unit.
4) Once the retainer ring is out, take a pair of pliers and slowly pull the back plate out. Do this with the pump back facing up and the pulley down. Otherwise the parts will fly all over.
5) Once you get the back off you will see two pins holding things together. Pull these out and the plate they hold in.
6) When you get the plate out you will see the rotor and 10 little vanes. The vanes simply slip out. Pull them out and set them aside. The vanes go back in with the curved edge facing outward.
7) Push the rotor out of the pump itself so everything except the housing is left.
8) Turn the pump over so the seal is facing up. With a screwdriver pop the seal out by leveraging one side against the other
9) Tap a new seal into place with a socket that is about the same size as the seal and a small hammer. Make sure you seat the seal. You will hear a different sound when you hit "home".
10) With the unit all apart take a pick and remove the old o rings and insert new ones. Put a little grease on them so parts will slide together easily
11) Put a little oil or grease on the lip of the seal and turn the unit over and put in a vise with the seal facing down. Put the rotor back in carefully so you don't cut the seal.
12) Put the round plate in which the rotor turns on and place the pins back in place securing the round plate to the housing.
13) Put all the vanes back in. You can use a little grease to hold them in place so they don't keep slipping out
14) Put the top rotor cover back on and over the pins. The only pieces you should have left now are spring, the back plate and a pulley. You can tell how it goes on since there will be a silhouette of how it came apart
14) Take the unit out of the vice with you still holding it with the shaft down, get a large socket and place it over the shaft. The socket should just go over the shaft and rest against the housing.
15) Place the spring down on the plate inside the pump. It only fits one way where it seats on the flat plate.
16) Put the end cap in place and put the large C clamp with one foot on the socket and the other on the back plate. Slowly increase the pressure on the C clamp until the back plate is far enough in to start putting the retaining ring back in. Be careful that back plate gets cocked sideways easily and if you are not careful it will get wedged. As you are increasing the pressure on the C clamp, slowly go around the back plate tapping it with a hammer and flat punch, just to make sure its straight.
17) Once you get the room and the retaining ring back on, all you have to do is put the woodruff key back on , then the washer and nut. Tighten nut, good to go.
The reason I went farther than just doing the seal was two fold. 1) the parts were really no cost and 2) Like everything else on the car I found the old O rings to be brittle and hard. While they might have worked, its just that since I had it this far, it just made sense to go all the way. Good luck