So it seems that the easiest way to fix this is just to take the pin out of the arm, glue the grey bit back into place and put it back on. I filed down the tooth on the grey bit and had to build it back up with some glue so it was a bit tighter in the end.

 

Hmm, I opened my Grimlock a couple of hours ago, and guess what? His right dino knee/robot elbow has popped the little grey bit of plastic out!

Hmm... gotta work out how to pop it back in.

 

I posted about all this stuff and how I fixed mine in the feedback thread weeks ago, for the sake of simplicity Ill compile my posts below

I haven't gotten the stress on my grimlocks arms, however I glued the the ratchet in place before extensive (or minimal) play, because the amount of wiggle was annoying me, and his elbows are still looking good, no stressmarks or anything, and it has been through extensive play courtesy of Christmas spent with my family I let a bunch of kids play with him

So either I got lucky, or gluing the ratchet piece into the forearm helps to desperse some of pressure that is caused when bending the elbow, or a bit of both

I suspect the cause of the problem is the small grey ratchet, because of the way it literally just sits entirely unanchored and loose in the forearm, when you bend the elbow down the ratchet becomes unseated and presses itself on the interior wall (the one that's breaking) as the resistance increases, all of the forces and pressure are pushing on that wall, causing large amounts of stress, and eventually failure (breakage)

By gluing the the ratchet to the bottom of the cavity, when the the elbow is bent down, the pressure and stress is now concentrated on the spring ratchet, (where its supposed to be) and the glued connection

Yes, though it might be possible to do without removing the pin, but it would be more tricky, but I will say that because the pin very short, it is fairly easy to remove

There are two things to be aware of in doing this

1. The direction you need to push the pin out, in the pic the forearms are facing forward and the arrows show the direction I had to push them out

Edit: the direction of the pins in your figure may be different, make sure to check before you push them out

2. Make sure when you glue in the ratchet (the little grey U shaped thing) that the tooth (the ^ shaped thing jutting out on one side) is facing up with the closed end of the U facing forward, as shown in the pic



Otherwise I would direct you HERE for a pin removal tutorial and mention the pin is roughly 1.95mm/.077in in diameter


These are my firsthand impressions on the cause of the breakage, feel free to pm me if you have any other questions  

 

Annnd fixed. Popped the leg off at the knee, popped the pin out, glued the grey back in, filed off part of the lead ratchet, soaked it in boiling water to reduce the stress mark, reassembled and voila, you'd almost never know anything had happened.

Just seems like the lead point on the black knee is a fraction too square, so it catches the grey part and lever it out. Pretty easy fix, but really shouldn't have had to. I can post pics of what I did if anyone cares.

Edit
Just saw Sponges post. FYI after glueing the grey piece in and reassembling, the leading point on his black knee part still caught against the grey spring thing which would have levered it out again. So I had to disassemble and then file away that bit of the black piece.

 

It does still catch, however the strength of the glue determines if it will lever out enentually, there was so much play between notches, that I didn't want to shave the tooth down cause that could make the ratchet even worse, the glue shifts the force to the bottom corner of the U, and because the force is being applied from a fairly small surface area, that bottom corner act as a fulcrum wherein the only way to lever it out, would be if the resistance of the spring could not be overcome, and the forward force was enough to overcome the glue in a lateral orientation (the most difficult direction you could try to remove them in)

I'm pretty confident the ratchet would break at the spring before the glue gave out, given of course the glue was set well and developed no bubbles or layer issues, filing the tooth down will definetly help to minimize the wear, I was just concerned filing it down might make it more floppy, thanks for adding your exeperience, I might do some light filing now!

 

Just wanted to throw in that my steeljaw figure is having a ratchet joint issue too. Both of the elbow joints on my figure are super stiff to the point where I'm afraid to bend them

 

just finished fixing my grimlock. he's a lot better now.

 

Some pics of what happened to mine.

His arm after the grey piece levered itself out. A lot of stress marks there. Also, I think it may have stretched the plastic too, because the top of it is now curved, whereas on his left arm it's straight.



In the end I popped the arm off, unpinned it and glued the grey piece back into the gmain green arm. I then sanded down the leading point on the black piece which was what caught against the grey piece in the first place.



After it was all put back together I dropped the lot in boiling water to reduce the stress marks. It's still visible, but it's a hell of a lot better. If I wasn't looking for it I'd miss it. But comparing the left and right arms at the lower elbow, why is his right curved, and straight on his left arm? What gives there?



Finally I think if you sanded down the piece straight away you'd avoid all this in the first place. If you pop off the arm like I have here, it's possible to sand down the point in question without dealing with the pins.



Anyway, hope this helps someone avoid the mess we all got into.

 

I think the right arm just has a curved bit anyway on some of them. No idea why.

 

thanks for the tuto, i fixed my Grimlock before he had the occasion to break

 

That pin just doesn't want to move, so I put glue on the gray piece and forced it in place through its hole. We'll see if it works that way too, there's more than enough room.
If push comes to shove I'll just glue the whole elbow in place waiting for another loss of wisdom and the purchase of a second Grimlock.

 

Aaaaand nope. Going back to the store to get it changed with a new one which I'll fix before even trying to pose it.

Wish me luck.

 

Did anyone ever verify if Takara's version has the same problem?