Step 5:
Assemble the long screw in the kit to the smaller of the 2 black plastic parts. Do not thread it all the way in tho! Fit this into the slot on the end cap.
Look at the other centering assembly for guidance, but again do not do the long screw up at this point!
Step 8:
Reassemble the end cap, making sure that you have positioned the stick so that the lug indicated in the picture locates on top (or on the bottom, depending on how you want to look at it ::) ) of the arm. If you have to force the end cap on, you do not have the stick correctly positioned!