Hey David,
found some snaps of the remains of the probably original system.
The metal ropes go to the front panel where the controls where located. The hooks which you see on the picture presumably went to the valves in the wing. But the valves and the water bags where missing when I got my 15. Schleicher told me around 2014, the two bags without the valves would cost roughly around 500€.
On the second snap you see the copper tubes which go to the bottom of the fuselage
the upper part must have been connected to the valves in the wing.
In the Forum you will find more solutions which defer form the original.
Best regards, Max-I
