The stupid balljoints in its feet are loose as hell and if I do managed to make it stand without toppling forward I can't do anything with its pose. There's no way for me to lock the feet into place with the joints like that. Oh and my MP-05 always lean to its right due to the massive cannon. Anyone else having these kind of problems?
If all else fails, do what I do to tighten ball joints: Pop off the foot. Fill the cavity with hotglue from a hotglue gun. Quickly pop the foot back on. Give it a wiggle, wiggle and it should be nice and tight.
Put some kind of glue in them, then move them around. Try not to use superglue though - if you stop moving, the joint will be locked up forever.