Here is the image/post:
If it’s not on the wiki, I’ll see that it gets added now.
Just because the router is new doesn’t mean that it doesn’t need new brushes — could be a bad set, and it doesn’t take that long spinning at 5 or 10 on the dial to wear them down in CNC timeframes — the trim routers are intended for brief (by CNC standards) handheld usage.
The only other thing I can think of to try which a search of this page doesn’t reveal is a USB isolator — if you can’t find one locally I’ll suggest that we send you one if the wire mesh (and if you haven’t tried them, USB cables w/ ferrite beads) don’t work out.
That it only occurs w/ certain paths is interesting, and I believe worth mentioning to one of the electrical engineers on the team.
I added the wire mesh @DJ_Valenski noted in the above post to: Shapeoko CNC Router, Rigid, Accurate, Reliable, and Affordable — there are a few other things which you could try if you wish between now and Monday — please don’t do anything which you’re not confident you can do safely (still not wild about listing the re-wiring the router to have grounding).