Hello, sorry for my bad English. Newbie AND French, I’m moving slowly, but I’m still moving 
Calibration is not as difficult as I feared, and I was very impressed when measuring distance between 1-2 and 3-4, and found 1914mm for both!! but the Ridgid router with the Z-axis engine seems to be causing me the same problems as yours, @eightlines. It loses its zero point because the router is coming out of its lock slot. I made a video here:
http://tousauxabris.org//docs/IMG_0849.m4v
I think I do not need for the moment to change the sacrificial orange button.
I did not install yet bungee cords or tensioner to my Ridgid (AEG in France), but will do.
I’m not sure I understand your solution, especially when you write that you have “tightened the housing clamp to be as tight as possible”, when I also read “the clasp needs to be loosened” in another post, here:
Can you please send a photo with arrows that shows your intervention to the different points on the Ridgid? (the best would be a video, even with shaky cam, as I did myself) 
Thanks!