Please pay attention: The plastic screws are used on the axles and rotational joints, and the metal screws are used to attach parts together. And at the 1:58, the upper plastic rod needs to be replaced with the brass one as well as the upper one at 2:50, 4 plastic rod (18 6 mm) need to be replaced with brass ones (18 mm) without thread. Also 3 longest (34mm) plastic rod needs to be replaced with brass ones too.