Rigging the blocks correctly is usually overlooked. When setting up 2 and 3 pulley blocks, the blocks are laid with the first block perpendicular to the second. With a 3 block, 3 pulleys in the block, the running end that you pull on goes through the center pulley on the top, down to the rear of the bottom block and across on the back side. Up to the rear of the top and through to the front. Next to the bottom on the same side and across the front bottom pulley. From the bottom front pulley up to the front of the other side pulley at the top and through to the back. With 3 bottom, go down to the rear, through and tie off at the top block. If it's a 2 block set up, you tie the dead end to the bottom block. That way the pull is straight and balanced evenly on each side of the block. If the blocks are placed with the pulleys all in the same direction and the line (rope) running across, top and bottom the same, the lines will twist since one side of the pulley is stressed more than the other side.