Bit at the top looks nothing more than two fingers to ctr the rod and a stop
I would think you measure it as shown in the leaflet, flip it over and note any difference in readings and then tweak (technical term) it until you get the same readings either way up.
If it rocks on the machined top of the "V" then you have also got some twist to take out.
J
Edited By JasonB on 13/05/2016 13:16:32