RE: Core One crash/restart
I had this issue as well. when the printer goes from rear right side to front left side, I notised that the left rear motor moves but the other one almost stay still, when the printer restarted like a power cut. Grounded the left rear motor, problem solved. I fastend a cabel on one screw that fastend the motor. and other side a random spot on the frame
RE: Core One crash/restart
I added the star washers to both my X and Y axis motor, verified I have continuity from the frame to each motor with a Fluke Voltmeter. I have been printing for over 10 days without the issue popping up.
RE: Core One crash/restart
I had two prints fail this weekend with a ton of travel and crashing. While I wait for my 3mm washers to arrive I cut a test lead up and that same print ran last night without issue. Seems like the answer. I’m going to set up my o-scope and try to measure this someday. 
RE: Core One crash/restart
I had two prints fail this weekend with a ton of travel and crashing. While I wait for my 3mm washers to arrive I cut a test lead up and that same print ran last night without issue. Seems like the answer. I’m going to set up my o-scope and try to measure this someday.
In my case I just scraped away some powder coating from around the screw hole. That was enough to get a decent ground connection.
RE: Core One crash/restart
I ran into this issue and fixed it with star washers as well. What's odd to me is how the printer ran fine for months after assembly and then suddenly started crashing almost every time I ran a print. I did just change the filament spool before that but it was a new spool of the same material I had already been using. Maybe the belt tension has changed over time which somehow leads to this problem happening more often or earlier in a print with diagonal movements?