I finally got around to investigating why the wipers weren’t working. It seemed the motor was getting 12v at the earth feed and this was going through and out of the inputs. This is because in the Mazda SDV build manual it’s how the wiring motor loom is spliced into the Mazda loom.
This is only incorrect if you’re not using the Mazda switch gear. If you’re using aftermarket switches, swap the earth and positive feed around (pins 1 and 4).
With the wiper motor working I clipped the wiper arms/blades on.