Wind the spring loosely and insert before tying the rope to the centre. The
centre can then be turned by hand until the spring is wound and the rope can
then be inserted and tied on some models. You may need to tape the end of
the rope with insulation or similar tape to a length of clothes hanger wire
to insert it. On other types, the rope can be replaced with a longer piece
of rope that is then cut short.

Spend a little time playing with it, but don't cut yourself on the sometimes
sharp edge of the spring, or release it in a hurry into your face, don't ask
me why I know!!!!

Hope this helps,
Pete