I agree, lets see where this goes. If nothing else it will teach.
Like others have said, you can not use gravity to add energy to a device, except for the first cycle. After the initial boost, you need to put more energy back in to get the same power boost out again. It will ALWAYS be a net loss of power.
Once the device is completed, I would like to see a scientific approach to measuring the efficiency. Use a DC electric motor attached to the devices input, and measure the DC motors voltage and current to see how much power you are putting in. At the same time, use a dump load on the output of the device, and measure the volts and amps again to measure output power. From this you can work out how efficient the device was.
Once you have your power in and out figures and the overall efficiency of your device, remove everything except the F&P, and again use the DC motor, and dump load to measure the power in and power out. This will give you another efficiency measurement. In both tests, the motor and F&P need to be running at the same RPM, and the load resistance also need to be the same to reduce errors and the effects of power curves of the F&P and motor.
I'll bet my testicles the 2nd test was more efficient. Like I said earlier, you would be better off just sticking a crank handle directly onto the F&P.
Glenn