A common request for help starts "My steppers make a noise, but don't turn" Those symptoms are exactly what you would expect if the motors are wired incorrectly. Openbuilds have stepper motors made to their specification, so our motors match our latest wiring diagrams (OpenBuilds BlackBox 4X Documentation). If you got your steppers from somewhere else, or have had them for some time you need to know that the colour coding of the wires on stepper motors are not standardised. Electrically, bi-polar stepper motors used for hobby cnc machines have two coils of wire - you need to find the pairs of wires connected to each coil. Disconnect the motors and check with a multimeter on continuity or resistance to find out which pairs of wires are connected to a coil (low resistance or continuity beep) . Treat one pair as A+ and A- and the other as B+ and B-. To make life easier disconnect the motor you are testing from the drive pulley or leadscrew and check to see which way it turns. If it turns the wrong way reverse A+/A- OR B+/B- and it should turn the right way. Come back to us if that doesn't solve the problem.