Frage DL445 Laser Alignment

Done a job carving then changing program to add some Laser engraving to the same job but found the alignment was out - had to scrap that one. Another has come up so I need to solve it, I used the Plotter pen on both UCCNC Carve and Laser programs and adjusted both programs Backlash to Y axis 0.1mm and they both run True with the plotter pen. Rerun the same program with the Laser connected and the alignment is out, this tells me the Laser is not true - what can I do ? I have a D600, running the Performance Kit, DL445, Kress, Plotter Pen, Diamond Drag and 4th axis, located in a spare room so temp is not an issue, everything runs with each other except the Laser ?