"The output of yours appears to be about right for the early models but I have a concern that yours may not be working. You should only be reading about 4.0 volt to 4.5 volt with a multimeter / voltmeter because of the 50 percent duty cycle."
Yes, the volt-ohm meter reading is just over 4 volts - I had taken the duty cycle into account when I estimated 8 volts.
I went ahead and used a recommended concentration of saltwater, which is 1 teaspoon of salt in a cup of water, and there was no improvement in current compared to my ad hoc method for doing the same thing. In fact, I was typically passing about 0.1 milliamps (actually 0.2 milliamps peak to account for the zero voltage half the time).
If the Parazapper indeed puts out that much current, then it is arguably a much more powerful apparatus, presuming that current is important for its effect (which it should be). But how can you guarantee that level of current? Is there some sort of electronic means to fix the current, or are you estimating that based on certain practices that you specify in the instructions for using the device? If the latter, then this assumes that each person is using saltwater soaked paper towels and are doing it the proper way.
In the diagram for the Hulda Clark Zapper, I see that there is a 1 kohm resister in series with the output, I guess that one way for allowing more current would be to reduce the size of that resistor. However, based on the levels of current that are being passed, reducing that resistor will have little impact. If I short the paddles and I get 4 milliamps (with 1 Kohm resistor in series with the paddles), and I can pass less than one tenth the current with one paddle in each hand, then that means that the interface of the paddles with my body and my body itself is presenting a total of over 10 kohms of resistance. Thus, lowering the value of the one resistor in series with the paddles will have little impact on the current passed. In fact, for me to get to 9 milliamps (assuming the same resistance is being presented by my body), I would need to increase the output to 90 volts.