@jay_s_uk Thanks mate. I think it's to do with the positioning somehow - I agree with you that - I think it's ignoring the M9 command but failing on machine limits.
I've homed my workbee, then moved it away from the corner a bit and set my work co-ordinates.
I think I'm setting lightburn wrong somehow. I'll have a play and come back to you! Thanks.
@o_lampe - OK that works - the laser came on, went off - Yessss! No just need to figure the lightburn setup to create the right g code.
@jay_s_uk Thanks jay - I think I'm there....it's coming on and off anyway as planned - I noticed that the frequency F1000 line in the gcode seems to be controlled by the mm/sec speed setting in Lightburn - when I changed it to 500mm, it changed the gcode to G1 x160.587 F500 and the laser didn't work.
Changed that to 1000 mm/s and it worked. Also added S1 too and works fine.
Thanks for your help mate, I really appreciate it. I can actually use the thing finally! Awesome. Owe you one. Thanks so much.