First thanks for the plug design, it works great!
At first I had to open the K3 to check continuity, because the TX pin did not touch the metal. Maybe that's your problem, derpeter?
By doing so I also inspected the connector from the inside, and I don't see the need for a notch (but two of the pins can be made shorter).
I also used a bus pirate, but getting the 1.8V from the Kindle did not work: there seems to be a 51Kohms resistor inside, and the BP draws too much current (ie has a too small resistor). Could somebody confirm this? Getting the power from a standard 1.5V battery worked though (it reads 1.6V). Not sure if it is safe to have RX greater than Vpullup. When I plug Vpullup on the K3's 1.8V pin, it drops to 0.4V. Maybe you should check the voltages, derpeter.
If you tell us which files you need we could perhaps send them to you.