The gears and belts that make up a printer's X and Y-axis can wear down over time. This can cause gears to skip and cause the printer to lose its place. It is good to always lubricate metal-on-metal parts as well as check belts and gears regularly for wear. Your gears for the axis can also slip if the travel speed is set too high or if the movement belt is set too loose. We recommend lowering the travel speed and tightening the belt to see if the issue goes away.
Printers are very delicate while printing. Any movement or jolts can cause prints to fail or gears to slip. If your printer is moved at all during a print, this can cause the belt to slide a few steps and cause prints to be misaligned.