All right, here's another tutorial to repair a broken Ryuki based figure. To view the tutorial on how to fix his knees and elbows, check this out:
http://kriderworld.blogspot.sg/2013/04/hi-well-for-starters-i-havent-been.html
In this case its Ryuki himself.. or rather maybe ouja since his base body is black. I bought this figure as is without box but it was only much later i realised his abdomen is actually broken. The plastic bit serving as the hinge joint between his chest piece and the abdomen has broken and I didnt realise it until i move his abdomen around and felt the break. The good news is, it is actually quite simple to fix this and even make it more poseable as a bonus. The bad news is, you need one of those joints you see on the photo above to reconnect the broken joint between chest and abdomen. You can use a Revoltech joint but that means you will need the glue the 2 points of the revoltech joint to the chest and abdomen piece restricting the chest piece to swivel horizontally separately from the abdomen. True that the original swivel joint doesnt cater to that either but hey its an improvement every one would like to have.
The first thing to do is to clear out all the broken joint pieces in the abdomen and the chest piece. Use pliers or blade to cut or pull them all out. You will be left with a flat surface on your abdomen piece and a hole on your chest piece. You will need to cut off some of the plastics at the upper abdomen piece. This is to allow the joint to fit in nicely and allow it to swivel well.
For the repair, you just need a ball joint piece and a socket joint piece (see photo above again, the joint parts icut off from the main pieces).
Now drill a hole on the abdomen piece at the spot where the hinge joint was. See photo below. This is to allow the ball joint part end to be inserted in.
Now glue the ball part on the abdomen like so:
For the chest piece you dont need to drill anything as there is a hole (where the hinge joint used to be) there already. However, the hole will be too big for the new joint. You will need to use putty to seal the hole and the socket joint part on it. See photo below. Thats how you insert the socket part on the chest piece. Putty was used to make to keep the socket stuck on the chest piece. I strengthen this with super glue as well.
Once everything dried, you will have a better joint between abdomen and chest as they can now move independently of each other as well as swivel horizontally and vertically (a bit limited) as well!! See photo below but ignore the wierd hairdo ;p
You will find the broken plastic hinge piece on the chest piece is actually removeable. It connects to the chest piece with a teethed rotating pillar. Heat the broken plastic piece with a hairdryer for 15 - 20 seconds. Now carefully use a plier to remove the broken plastic hinge piece from the chest piece without further damaging the plastic hinge piece. Once you have removed this piece, sand the surface where it is broken to allow better glue adhesion. Dab super glue on one side of the broken surface, place the hinge joint over the metal rod again and try to glue the hinge joint back. Do not put too much glue or the whole joint will permanently stick together. You can put a generous amount of glue on the broken surface but you will need to continuously move the hinge while the glue sets in to avoid the glue from sticking on the metal rod as well.
Let the glue dry for half an hour or more. Now, once the joint has been repaired, use hairdryer again on the teethed rotating pillar on the plastic hinge piece and the hole on the chest piece to soften them up. Reconnect the plastic hinge piece with the chest piece and let it cool down.
This will repair the broken abdomen joint. Mind you, this is not a preferred solution as the hinge joint between your chest piece and abdomen piece may not last.
Hope this helps!