How do I repair loose arm joints?
I have been experimenting to find the answer to this question, and today I have finally found it. I stumbled across a youtube vid of a child explaining his method, and mine was built off of his.  His idea is to take labels, cut them into tiny pieces that are stuck onto the arm at the point where it connects into the torso. This works, all too well. Here's the problem. The arms get incredibly tight, as a result of there being too much pressure. This pressure slowly puts stress on the torso, and within weeks you will notice the modified figures busting open at the seam off the torso. This is generally on the sides, at the base, and it slowly cracks it's way up to the armpit permanently destroying your figures. I found this out the hard way when 10 of my superhero figures were destroyed. Still, I am thankful because this lead to my discovery. Once the figures had been destroyed, I quickly removed the labels from all the others I had done, to stop them from suffering the same fate. What I realized was that once the arms had been doctored, after removing the label (I used small pieces of a cat hair roller, and I'd advise you use this because I'm not sure labels are sticky enough) the arms retained Their clutch. This is a result of the stickiness staying with the arms after the sticky paper/cat roller material had been removed, but it feels like a perfect arm. The clutch is there, and you will not have to worry about the torso cracking. So now that you know, don't make the same mistake I did. This is what I would advise. 


Remove the loose arm.
cut a small square off the cat roller. 
place it on the connected part of the loose arm. 
insert it into a torso that you have double of, or don't care about.
set it down, and wait an hour. 
remove the arm, take off the sticky paper. 
carefully insert arm back into the original torso. 


Now you have a perfect arm. It has amazing clutch, and best of all because the clutch comes from a sticky texture instead of immense pressure, your torsos will stay intact.