Fader Puzzle - any ideas?

[Terry]

As an aside, law bending resistors  require a low impedance drive for accurate results.

Are you sure about that, Jeffrey?

Surely if you add the series resistance to the pot value when calculating the value of the law bending resistor, you should be able to find a value that gives the required law over the part of the curve that represents the pot.

Obviously, if you don't take the series resistance into account, you will get the wrong answer!