Have you considered that you may have it wrong end to? In my experience the z bend on the spring usually goes into a fitting on the self propel unit and the other end of the cable connects to the handle. The ball on the cable end fits inside the cone that the spring forms.
#3
StarTech
According the IPL he is trying to install correctly. OP just look at the wear pattern on the plastic piece for tell tell signs of the previous location.