Many things can lead to creep but wear is the most common. You may be able to adjust the creep out but many times parts are required to bring everything back into spec before you can get it spot on. The LX565 has plastic guides that wear as well as the centering spring bushings that allow the controls to move side to side instead of linear. With side play the machine will always have trouble returning to zero. While you have the parts out for inspection make sure the dampers and their ends are also good and not worn to the point of causing issues. All the centering adjustments can be done with the seat up. I have also seen several of these units that the sound deadening material on the bottom of the seat pan was contacting the centering plate and linkage to the point it would not return on its own. Lots of things to check and I would suggest a service manual for the proper procedure.