Husqvarna 531 11 91-74  Sealing

The purpose of the Seal is to protect shaft, tubes, valves, and bearings from intake of dirt and debris, and prevent fluids from leaking out. Replacing a damaged seal can prevent the more consequential damage to other parts of your outdoor power equipment. Improper assembly, excessive wear, poor lubrication, and contamination from debris can all damage seals and require replacement. Be sure to adjust the seal tightness when installing to prevent the leaking of fluids.