Thanks everyone. I'll bite the bullet and upgrade now then.

@bearer That's correct. The only thing that stands out to me is that its the last move in a section followed by M5 (laser off)

Hi @FelixH,

Yes, this is repeatable. The gcode file has 10 repeats and the laser is off at this traverse every time.

I've got a Duet 2 driving an Ender 3 with a laser module attached. I'm using the PWM circuit from the Duet Wiki. Its working well but it occasionally does a cut move with the laser turned off.

In the attached gcode file, the laser is off for line 1937:
PCB Jig 100x70.gcode

1936> G1 S255 X57.50 Y146.00
1937> G1 S255 X88.70 Y146.00
1938> M5

There are many similar lines in the gcode file so why does the laser turn off for just this one?