I3 Pro W: z axis motors shudder at random times, and get out of synch with each other

[mistermagoo2you]

Greetings!

I have a Geeetech i3 ProW 3D printer. I received it from my wife, who had bought it on Amazon as a Christmas present.

Well, I've assembled it - the electronics appear to work, and aside from some wiring harness issues, the assembly is complete. It does have one big problem. When i get the thing to move in the z axis (up and down), sometimes one side stops and the stepper motor shudders. THe other side keeps going. This will happen on both sides (not at the same time). You can see it happen in the video when you have a look at it. You can view the video at https://www.reddit.com/r/3dprinter/comm ... w_printer/ .

The table that the printer is sitting on is levelled, the bed is levelled, and at the beginning, the adjustments are made so that the rails that the extruder is sitting on are parallel to the bed. However, once the extruder has moved up, the rails are no longer parallel to the bed. When I hit the autohome command, the extruder will return to the home position - but the rails may not be level.

What could be the problem with the printer? Do the steppers need more power (a mainboard adjustment)? Any suggestions about this issue and how to fix it are greatly appreciated!

Regards,