That's the detent for a fully closed (folded) kick start lever. Look in the splined base which you ordered (female) which fits on the kick lever shaft (which is also splined,but male) there is the hole where the actual kick start lever fits. This in the same plane as the little indent in the lever it self. Put in the spring, Then the ball on top, press the ball down with a small screwdriver or whatever from one end as sliding the lever in from the other. Once the lever end has started over the ball just push in all the way and turn to engage the lever a couple of times to make sure the detent works. Then slide the unit on as you would any kick start lever.
I did this in the field yesterday, so its not difficult. I used an allen wrench to push the ball down. Took maybe a minute.
Hope I did not over explain, its pretty obvious if you look at it enough.
Good luck.
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