The lower leg armours are held by clips so you just have to open through the gaps gently. If it's the ball joint loose, you can access through the foot bottom by unscrewing to reveal then you can tighten the ball joint cup.
Yes, there is a ball joint but please don't force it. I just unscrew and open through the gaps but there is no reason to open it, i did because it's the only way to glue the broken piece back.
Broke my Mark 7's leg..... looks like a brittle and thin metal. If you can't turn your ankle left and right, better to loosen the ball joint.
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