9g servo arm top coupler to threaded rod

One thing lead to another and this thing is completely rebuild & a new concept builds upon the existing servo arm, resulting in less fiddling with tolerances and a bigger, more rigid part (as the printed adapters are weaker).
While the squeeze-fit solutions and such where nice, I decided on adding a M2 nut to the M5 threaded rod holder.
Thanks to FlouSH, Talpa and also Zippy for the ideas & comments on the initial design(s).