There isn't anything "magical" about wiring, especially in that application.
You can literally "reverse" the path and by elimination, see what every function can do. Like the elevation motor.....set up a 12 volt battery, and I know this may sound ridiculous, but it is how I taught basic electrical application on aircraft, and use a wooden block, and set 2 machine screws with wing nuts if you have them, or just alligator clips....have a red ( + ) and a black ( - ), and then start checking components.
Take the elevation motor, which may be a simple 2 wire hook up, and make some leads, and check by holding to the terminals you have made. That is testing. If the motor has more then 2 wires, one may be a ground to frame, and each of the other leads may be direction. Black is typically a ground, but not always. It can be a floating ground, and that is why you use alligator clips...to just "touch wires to terminals" to test what you are doing and not risk burning something. Also why we use a battery to test, instead of a charger, or transformer. Pure direct current.
Now, to figure out the switches, use an old trailer tail light, or tag light lamp, and attach it to the board, and make sure it is grounded back to the black. Then you can use it to determine if the how the switch works, and if you had 2 lights, set it up so you can flip the switch and see each direction the + side puts out to run the elevation motor.
The motor that feeds the head may have a rheostat, and that component is tested using a light bulb also. The speed of the motor is dictated by the voltage allowed through the rheostat, and thus, if the switch is working, the bulb will be bright to dim to off as you rotate the speed control.
You can also see any of these functions by the use of a volt/ohm meter, a cheap one costs $5 and is suited to simple tasks like this. It isn't like you are looking at ballast resistors and diodes and such.
The stator wire from the motor probably means there is an internal voltage regulator, so it is a simple, one wire hook up to battery. You should have 13 - 15 volts on a volt meter if it is running correctly. Or a simple 12 volt light will shine brightly when the engine is running, if it is producing power, and be less bright when just off the battery.
Hope this tutorial helps a bit.
