You could try clicking the x axis switch with your finger and see if movement stops. if it does, the switch isn't positioned correctly or the arm is bent (bend it back). If it doesn't stop, either the switch is broken, there's a wiring problem, or it's not plugged in correctly or plugged into the wrong port on the motherboard. Usually you can't plug them in backwards, but if it was, that can make a difference- turning it from a momentary on switch to a momentary off switch, or just causing it to not work.