Just finished the assembly of my x-carve. When trying to engrave Richard, the machine keeps engraving the letter R over and over again about an 8th of an inch atop of the previous letter R.
If it's moving every time it tries to carve, that's an indication of losing steps. A forum post that addresses lost steps is https://discuss.inventables.com/t/guide-offset-cutting-lost-steps-positioning-errors-etc/16084, and would be a good place to start.
I have also uploaded a few videos related to maintenance and troubleshooting, you can see what's available at https://discuss.inventables.com/t/x-carve-maintenance-troubleshooting-videos-add-your-own/13405. You may be most interested in the videos on belt tension and potentiometer adjustment, since those can cause lost steps.