@MakerJim this went through my head too.
I had one instance that it happened when using my mini rambo that I had wander. but not like this.
Like I said, the pen drawing test was just fine - this was to test accuracy without any load. it seams that when its moving the router through the wood that it wanders.
I’ll check my grub screws as Ryan mentioned and go from there.
I did notice that I have a crack in one of my parts, so who know is there aren’t other crack and weak spots that effect it too.