i dont have a tutorial per se, but i did tell matt how its done.
gently pry off the 3 armor pieces, i usually take the elbow one off too to make it easier to get the rubber sleeve off. when taking the rubber sleeve off check around every hole and seam for excess glue that could tear the rubber or prevent it from moving. roll down the sleeve from the shoulder and push it down while tugging the wrist portion. alternate back and forth til you slide it down past the elbow and it should come off the arm. take out the 2 screws that are in the forearm and elbow, one is slightly thinner than the other, keep that in mind because the thinner one goes back in the elbow. the forearm should split apart easily and you will have the 2 halves, peg, and upper arm w/ ratchet loop. in the ratchet loop you will see 4 holes around where the cog peg goes through, slice one of them in the middle with an exacto blade to give the cog peg a little extra give when it rotates in there. repair the broken plastic, let it dry, then install the peg back into it and fuse it in place with more glue and let it dry. i use a small file to clean up any extra glue. then, reassemble the arm and test the joint. if all is well then put the rubber sleeve back on and reglue the armors. youll be all set. heres a couple of pictures of what you will be looking at when everything is apart:
