yes, I can see both the orange and green wires of the motor field winding. One end is twisted together and soldered to the terminal of one of the brushes.  The other end of the green wire goes to the middle connector just above the winding. The other end of the orange wire is soldered to the tab that goes from the motor to one of the terminals on the side of the e-unit.  The other terminal on the side of the e-unit is unused.  There is a wire from the roller wheel connection on the truck to the other brush of the motor and from there to the terminal on top of the e-unit. There is another wire from there to the engine's light, for which I have no bulb so that is open.