Because of the internal structure of the backrest, a certain amount of movement is to be expected and totally normal. This small range of motion helps facilitate your movement throughout the day, as the chair is designed to accommodate a variety of seating positions.
We do recommend that you tighten the bolt attaching the backrest and seat pan on a monthly basis. For instructions on tightening the bolt, you can view a PDF version of the assembly guide here.
If the movement feels excessive even after regular tightening, please contact us so we can determine if the movement you’re experiencing is within normal parameters.