To determine whether a problem lies in the stepper motor or the stepper driver or board check the following items. When connecting or disconnecting anything make sure the printer is disconnected from the computer and powered down.Connect the stepper motor connector from the axis with the suspected problem (for example the X-axis) to another axis with verified good movement (Y-axis). In this example we would, in Pronterface, select the Y axis +10 or -10 movement. If the X-axis motor moved without trouble or loud noise the problem would likely be in either in the board/stepper driver or the connections for that axis.Verify continuity of the following wire pairs: Black to Green and Red to Blue.
RAMPS Electronics (AO-100)
When using Pololu Stepper Drivers you may encounter the need to adjust the pot controlling the amount of current going to the stepper motors.Use a nonconductive screwdriver to make any adjustments to the pot. Using a metallic screwdriver can potentially short and damage the Pololu stepper driver.Gently turn the pot counter-clockwise to reduce the amount of current to it's minimum levelSlowly and gently turn the pot clockwise while using the movement controls in Pronterface to move that axis.Once the axis has smooth movement and travel check the stepper motor for excessive heat. It is OK if the stepper motor gets warm. If the motor is excessively hot you will need to turn the pot counter-clockwise to slightly lessen the the current.If the stepper motor makes a loud sound when moving adjust the stepper motor pot to provide slightly less or slightly more current.