Is this because of the grub screws? (because yes, they were a little loose, the lock-tight is drying right now ) And could there be other causes? I made 10 passes and somewhere along the line it shifted to the right.
Grub screws can definitely cause that. Otherwise, skipped steps could be from something catching,/sticking or the bit hogging out too much (which is impossible in a laser) or a loose wire.
Hopefully it is the grubs. A laser has zero load. So it shouldn’t have any load related issues. Did you have any trouble with the router?