Marlin firmware. power not getting to D10 when needed

I have just hooked up a laser to my ramps 1.4 through the D10 output. I am using the D10 instead of the D9 because the amps are higher and sufficient for my laser diode.
I am having a little bit of trouble when the laser starts to operate. The steppers will start to make the path for cutting but the laser takes a few milliseconds to fire up and it is missing the start of the cut path. It is also staying on past the finish of the path about the same time.
Is there a small variable within marlin to get the laser firing up at the start of the path? and to stop an the end point?

I have had full success in the D9 output but really need to do some testing in the D10.
Thanks L

D10 and D9 are identical, both on the 5amp cct

D8 is on the 11amp cct