Working on custom figure: need help fixing joints.

Okay so this is a slightly weird one but I can’t think of where else to ask this really, so I’m popping it here since technically its a halo themed creation in working on. I’m going to be customising an old Reach figure I got (someone decapitated their Emile and lost his shoulders and seemingly fixed him up with a gungnir spartan) The figure’s pretty good but his knee joint is wobbly as hell. I can disassemble the ankle joints no problem but I can’t get the knees apart to do the same and start working on a fix. Has anyone know how to take apart the knee joint?

(Note, I’ve already seen that one YT tutorial with the Pink air assault Spartan and exhausted plenty of google search options. I wouldn’t come here and ask without have researched elsewhere first. I also know the Halo forums are a weird place to ask this, but since this is where people who own Reach-Era McFarlane figures are likely to be found I figured it’d be worth a shot.)