Look under the front of the cooktop and locate the pressure regulator. Remove the attached nut with an adjustable wrench.
Take out the pin that is inside the nut and turn the pin 180 degrees. Insert the pin back into the nut and re-tighten on the pressure regulator.
Remove the LP conversion label that is next to the rating plate.
Take off the grates covering the surface burners and remove the burner module. Loosen and remove the brass orifice for the burner with the adjustable wrench. Attach and then tighten the NG orifices for each burner.
Set the burner module and the grates back in place.