The purple square part that holds the lower knee joint, where the 4 screws are, tighten all 4 screws. for some reason those aren't tightened all the way in. Plus, pull down the top of the knee joint ( the black part) to tighten the single screw. This seems to be an issue with most copies of the figure. Fanstoys QC seems to be slipping further away from what they were known for. Hope this helps... Same here bro!!