At the flap end there is a circular track with a cut-out for the barrel shaped cable end.
At the other end, they are connected to the top lift frame.
When the top is raised, the flaps retract by coil spring tension, when lowered, the cables pull the circular wheels and cause the flaps to extend against the coil spring pressure.

I looked for diagrams in the service manual, but didn't find any.

I did find some stuff in the parts manual :