BM 470

The screws are loose
           => Tighten all visible screws
 
Lack of lubricant
           => Lubricate the joints and the two weight guiding tubes with silicone spray

Assembly problem
           => Untwist the cables and lay them on the ground. Then re-assemble the cables without twisting them.

Assembly problem
          => Check that the pulleys have not been over-tightened
          => Check that the cables haven't get out of the pulleys
          => Check that the cables have been mounted as per the assembly instructions