I will make up a test case with some simple concentric circles and re-run the burn and see if it hits the same spots.
I will also try using the EleksMaker software instead of LaserGRBL.
When I slide the gantry in the Y direction I can feel points of resistance at various points. I thought perhaps it was just resistance from the magnets in the motors?
Perhaps I should to a complete disassembly and test to see if each motor assembly slides on its rail freely.