Hello all! Recently completed my 0.2 build. I'm still going through the calibration process. I found Z stepper will move down, contact the Z end stop, move away from the end stop, then make a terrible ratcheting sound and will not move anymore. I can command it 1mm at time for about 5 or 10mm then it just grinds. The config settings look ok (I could be wrong). Could it be a defective stepper? I bought the LDO stepper kit. Any thoughts from anyone?