Total Preload
WARNING: This page is about a different car, the 2013 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.
Using a spring scale, check the total preload.
Total preload:
20.7 - 54.4 N (2.1 - 5.5 kgf, 4.7 - 12.2 lbf)
If the total preload is not within the specification, adjust the side retainer shim.
Courtesy of SUBARU OF AMERICA, INC.