WurstCollector
Super Freak
Take off his back section, where the batteries go in and you should see some screws. Unscrew this and the torso should come apart, be careful if it doesn't as its very thin plastic. If you get to this stage, also be careful of the head, as it can easily fall out of place and then the wires get yanked (messing up the eye lights).
After this delicate surgery is done you will have the torso in 2 halves, you can see how the arms are inserted and you can easily just take them out, and if its loose it probably needs more friction such as a thin coat of varnish or nail polish.
Let it dry and put it all back together, carefully making sure the wires are in a void and won't get trapped by the plastic shell of the torso when you are rescrewing it.
It is all really easy, I've had my TC14 (same mould) apart dozens of times thinking how to customise one into a death star droid (that hasn't happened yet haha)
edit: if this sounds absolutely terrifying due to the cost of the figure and you still want the arm tightened, I might be able to get some pics of mine apart sometime, if that would help!
It actually does, only because I'm clumsy. If you do have pics that would help tremendously. Thanks you for the steps on fixing it. I'm also worried about scratching the paint surface when taking it apart.