Print shifting to the side - belt tension?

[DeweyOxberger]

I have several parts of various sizes in a single print job. The center most part is shorter than the rest and the job will fail consistently as the center part finishes. All the other parts will shift about 1mm. Is this belt tension?

[djarmag]

Post pics of what you see, it can be belt tension, structure is mechanically loose, calibration not tweaked in EEPROM, try to focus on one object and see if you can fine tune to make that work, then add on to it.

[pouncingiguana]

Another popular possibility is not having the grub screws holding the motor pulleys onto the steppers tight enough. That'll cause all kinds of fun print shifting.