The power of simple is manifested in that others were able to build from the foundation Einstein identified and defined. They were able to accomplish things they most likely could not have otherwise. We also have experienced this phenomenon. Consider Ohm law. Georg Ohm did the hard work and broke down the complex to a simple law. We use the principles contained in that law as a starting point to understand the complexities of electricity and circuit dynamics.
You should be able to isolate into two groups any leads which have continuity with one another. The starting circuit is likely to isolate to two leads, the running circuit may have two or more leads that show continuity. If the running circuit has more than two leads, you will need to determine how those leads are to be used for voltage or speed changes.
The unshielded conductors radiate an electric noise field that couples capacitively with adjacent wiring. Stray capacitance at A & C cause ground currents to flow creating a magnetic noise field that couples inductively with adjacent wiring.
Occasionally, a technician or service person will ask me, "why not just increase the output by increasing the voltage (the current flow) to the motor?" While that may seem logical, increasing the voltage (in effect, creating an overvoltage situation) will not necessarily boost the output of the device. To understand why, you need to become familiar with a physical characteristic called "hysteresis loss."