Some sellers of the Sanwa JLF joysticks will try to save money by including a generic wiring harness not meant for it.
It will work perfectly fine, but the colors of the wires are wrong (black isn't ground).
Ground (the black wire) is the one closest to the edge of the PCB.
I don't think I've ever seen anyone on these boards mention ever getting a faulty switch, so it's probably not that.
EDIT: This pic shows the correct wiring harness with the black ground wire at the top.
