I impulse bought an Apple IIe Joystick on evilBay from the UK. 🇬🇧 "Untested, no returns."
Opened it up for cleaning - sure enough, someone already had a go at it. At first sight only some wires were snapped. Soldered them back, but the directions were reversed. Up was down, left was right, and vice versa.
Lots of head scratching later it dawned on me - if the axes are swapped, the directions are "reversed" on the pots. 🤦♂️ Corrected everything, it's working now!