The String
This is what Barry says about the string.
These are the beads I glued on the right side of the torso with two part glue.
I am still not sure whether the third bead on the little elevation (plywood) is needed or not and where is the best position to put it. For one thing it is surely helpful because it keeps the sting up and helps to keep it on the shoulder pulley.
For string I used a very fine fishing line and later a thin and strong thread.
One end of the string is tied to the hole in the shoulder and then threaded through the beads and finally through the leg traverse. I tied a thin copper wire to the bottom end of the string, just below the leg traverse, and threaded the wire through a final hole in the ankle and wrapped the wire around the ankle. It made varying the string length very convenient. (As I said earlier, I only used one string, not like Barry who used two. And it worked fine.)
This is the thin copper wire I tied to the end of the string.
These pictures show the string and the wire attached to the end but it is barely visible.
In these pictures I highlighted in the string with red. (Dashed lines mean it goes behind.) You can see the string is very loose here that is why the copper wire's loop doesn't touch the leg. The blue arrow points at the little hole the string is attached to on the shoulder.
The string is also attached to the shoulder with a drop of hot glue. (Blue arrow) The position of this attachment is very important for the bouncing back of the arms and the slowing down of the hip-flip.
The place of the attachment of the bottom end of the string is also very important. Earlier, I threaded it through the traverse of the leg and the hole in the ankle and wrapped the wire around the ankle.
Later, I found a better place of attachment. The blue dot shows the place.