Update: it seems the motor controller chip was at fault. Reprappro sent me a replacement board.by tepmurc - Huxley
I've just finished buliding my Huxley and started the commissioning. My y-axis, z-axis, and extruder motors work as they should when I send the commands from Pronterface. But the x-axis motor just vibrates. I've tried increasing the voltage (by turning the pot), doesn't work. I've tried even different wire configurations, but no difference. I wired the x-axis motor into the y-axis connectorsby tepmurc - Huxley