Tom: Are the RFMC documents still online?
I have taken the car side plug of my MC120 apart. Before I go into more details, please note that this is not an easy thing to do. I requires the use of many tools including some hard to get / purpose built ones. Taking the MC240 plug apart might be a bit different. Most parts that make up the plug are plastic or aluminum: use steel tools carefully or risk scratching and damaging the plug!
I took some pictures after I had it apart:
http://wegmuller.org/v-web/gallery/MC120TearDown (the gallery has two pages).
Here is my best recollection of the sequence (in these, I call the end of the plug that goes into the car the front and the end from which the cable emerges, the back):
1) Unscrew the plastic cable retaining nut (six sided nut from which the cable merges).
2) Unscrew the plastic retainer from the Aluminum six sided back of the plug. You are now done with the easy part.
3) Holding the main outer casing (the black cylindrical part you twist as you insert the plug into the car), unscrew the back aluminum six sided "nut". This may require significant torque as you will have to break thread locking compound (glue for metal). In theory, thread lock can be loosened by applying heat. Considering that the inner part of the plug is plastic, this may not be a good idea... There are three small springs that are in the end of the inner grey plastic core: remove them at once or loose them forever!
4) Now things get interesting. Using a piece of bent wire, carefully pull the seal from the front of the plug. The seal is like an O ring, only with a rectangular section.
5) You should now see a brass ring with six holes and three cutouts. You need to unscrew this ring from the core of the plug. The way I did it was to make a "wrench" by turning a couple of pins that fit in the holes but have a step to prevent them from falling through. Now that I've seen the inside of the plug, I think simple strait pins would do. Diameter is 2.6mm. A length of about 40mm should work well. My pins were a bit short, requiring the use of tweezers... The reminder of the "wrench" is a piece of flat steel bar about 3mm thick (1/8") and 19mm wide (3/4"). I bent it into a U shape, so it would fit inside the "trench" between the outer case and the plug core. Using a large adjustable wrench, I applied torque to the U shaped steel piece which in turns pushed on the pins that rotated the ring. On the inside of the outer case there are three brass pins (the ones that grab on to the car socket): they prevented my tool from turning all the way around, requiring frequent reset of the pins, using all three pairs of holes in the ring. To keep things interesting, the ring threads are held with lock tight. There is also a wavy washer spring behind the ring: it creates the friction for the rotating part. I suspect that the ring is torqued at a very specific setting when the plug is assembled...
Here is a picture of the tool installed on the ring, outside of the plug, for clarity:
http://wegmuller.org/v-web/gallery/albums/MC120TearDown/IMAG0225.jpg
6) Getting the ring out of the plug will require you to line it up so a cutout in its threads (inside diameter) clears the index on the core of the plug. Then you have to align the rotating body so the ring will clear the three pins that extend inward from said body. That's when three cutouts on the outer diameter of the ring body come in handy.
7) Unscrew the screw located in the middle of the grey sliding latch on the outer body. This requires the use of a "security" Allen wrench. This particular wrench is like a regular six sided allen bit, but with a hole drilled through its core. Those bits are not usually found in hardware stores. I borrowed mine from work. It came part of a set manufactured by Wiha of Germany. The bit that worked for me is a 5/64" Tamper Resistant Hex. There was, however, quite a bit of slop which leads me to believe the correct size is metric, possibly 2mm. You should be able to remove the grey sliding part. Some sliding and twisting of the outer core might be needed to free it completely.
8) Under the grey plastic part, there is a white plastic part. Between it and the outer casing there is a small spring (the exact same kind as in step 3). Remove said spring and twist the outer body until the white plastic piece lines up with a cutout in the plug core. It should be now possible to slide the outer casing towards the front of the plug to reveal the core.
9) Towards the rear of the grey plastic core, there is a small electrical switch. (it is the one that let the car and charger "know" the plug is ready and secured). Two wires extend from the switch following a channel in the grey plastic core. At some point the wires disappear under a blob of silicon. Carefully pry off the silicon. Mine came out in three or four pieces.
10) Now we reach a point where things might be a bit different for the MC240 compared to the MC120: the two wires from the switch (blue and black) are soldered to a purple and a green wire coming from the contacts. The solders are protected with heat shrink tubbing. There is enough slack in the wires to pull their connection points out of the rear of the plug. Cut the black and blue wires off right at the base of the heat shrink tubbing. I aslo removed said heat shrink tubbing to be ready for the eventual re-assembly. Now pull the wires out of the grey plastic core.
11) You can now slide the grey plastic core away from the metal front core. This may require some "convincing" as it is a pretty tight fit.
12) The previous step unveiled a black inner metal core. This part is screwed into the front metal part. Once again you will have to fight the thread-lock. The only way I managed to get it unscrewed was to hold the black part in a wise (with flat, non marring, jaws!) and, using a copper rod as a punch, hit the small locating tab (it held the grey plastic core in place).
13) On the side of the front inner core, there is a small Allen screw. Undo it and you will free the contact carrier out of the front inner core. Congratulations: you have now taken appart a Tesla plug!