GRBL MEGA 5X and Ramps1.4

Hi. I’ve made a rotary axis for my MPCNC so I’ve ditched my CNC shield, replacing it with an Arduino Mega wIth a Ramps 1.4shield. I have a couple of issues. Firstly an issue with my laser. It works fine from the CNC shield Z limit pin for PWM. I have checked voltages on the connector. 12v positive and negative with a pulsing voltage up to 5v on the PWM pin. All good!
However on my Ramps I am using D6. Again I have a good12v supply and pulsing voltage on pin D6. Connected to the laser it doesn’t fire. I have checked the min and maximum settings at 0 up to 1000 for that pin.
I’m stupidly baffled.
My second problem is that the E0 section on the Ramps isn’t sending signal to step+ and dir+. The wiring is fine as A axis works if I swap pin headers with X axis pin outs
If anyone can offer advice it will help enormously

What laser?
What LPS?