Nah going to check voltage on the laser socket and use that.
The gcode specific to repetier switches it on and off. So I want to try both.

measured the strutnuts and they're designed too large.
I'm slightly smaller (few huindreths of a mm) in all directions - which is what I've always found. So it's the design that's wrong.

Got an idea to try for a sort of 'supercharger' nozzle as well