G'day John,
Here we go.
Remove the outer cover, don't forget the circlip that holds the gear position indicator (the smaller circlip behind, sitting around the splined selector shaft can stay). To remove the spring, remove the spring anchor screw and withdraw the k/s quadrant and the remains of the spring. To install, fit the spring over the quadrant (do not hook the spring to the quadrant) and fit it to the cover, fit the anchor screw through the loop in the spring and tighten down. Now the tricky bit (I use a terminal screw driver but any small long, pointy shaft should do), pull the hook around and up to hook it onto the quadrant. See photos.
Notice the quadrant is sitting high and not against the bush because it's sitting on the hook.
At this position you should be able to push the quadrant down against the bush, this helps getting the hook into position.
Others may have better methods but this is the only one that I can find that works for me.
Re-fit cover.