In older models like 2.0 and 2.0S the center position might be misaligned after many work hours. This issue comes from a wear of the plastic parts that press the End-stop buttons.
If your printers nozzle do not center properly check following spots:
1. X Axis
The X axis End-Stop micro-switch is activated by a beam-like printed plastic part. In this case the issue can be caused by bended or damaged plastic part.
2. Y Axis
In case of Y axis most common issue is connected with the End-Stop distance (yellow PLA printed element on the picture) it might be detached or shifted.