It’s possible that there’s a hardware issue on the EggBot’s EBB driver board that is preventing the correct output signal from getting where it needs to. A thing that you could try as a test — quite non-traditional but possibly effective — would be to try driving the engraver from the AxiDraw. Place the AxiDraw in the very middle of its travel in both X and Y (halfway to the right, halfway extended), hook up the engraver to the AxiDraw’s EBB (in the same location) and try plotting with the EggBot software, to see if you can get it to run from that machine. Please let me know what you find.