I'm away from my machine but this has perplexed me all weekend. Machine is an R1 plus, not sure what version of Marlin I'm running. I am getting layer shifting on the X-Axis. It is different every time I print. Rotating the model and switching models doesn't seem to make a difference. Some come out nice other small layer shifts. Maybe 1mm. My X-Axis belt was way loose. I have cut that and gave it a much tighter fit. I am not seeing any missing ribs(?) on the belt. I've also tightened my screws on the gear/stepper motor. Didn't seem to make a difference. I've also added my lubrication to my X-Axis Rails., nothing appears to catch when I disengage the motors and slide my carriage back and forth. My extruder doesn't feel like it has play in the carriage as well. Could my stepper driver be going out? Should I try and switch the Y and X axis to see if the shift switches? Thoughts and other ideas would be great. Thanks. FYI, I probably won't be back for several hours. Writing this over lunch, and I wasn't finding anything much beside belt tension in the forums over the weekend. Thanks again.