Failure to install oil seals correctly can lead to failure. Factors such as knocking the seal into place may cause its spring to tilt in the bore or be out of alignment. Consider switching to a solid adhesive and applying it around the surface of the spring to prevent it from loosening.
One way to identify a seal that has not been fitted correctly is to check the rough shear of the rubber. To resolve this issue, align the mounting tool before positioning the seal in place.

Select the correct oil seal size