You must fix the harmonic-steel of that spring [pic 3]. When you pull the string, that spiral of metal wraps around the center, but now it is deformed.
You must also make sure, before you assemble everything, that by pulling the rope the spring does not boom from the central pivot.
Explain how to mount everything else appears somewhat difficult, given my limited knowledge of English.
The part about the spring is not easy, but not impossible. For the rest, i hope you remember how the pieces were assembled ... this is not difficult.
If I have time, send a photo-guide on how to disassemble and reassemble the string Shotter ^^
[EDIT: Kai-V me early....]
SE VUOI APRIRE UN BBFC NELLA TUA CITTA', LEGGI QUESTO LINK E CONTATTAMI!!!