I usually have a couple hundred 10K 10% pots in stock, so just for fun I tested a few. I had assumed that they would be ±5%, but it seems they are more like ±10%, or +5% -10% in my sample.

It also occurs to me that all the pots, when run to their limits, are all 0 ohm from wiper to that terminal. Does the joystick limit the pot to a portion of its travel, or does it go to the limits?