I feel that I am not getting normal service life from my jon boat trailer wheel bearings, I replace seals each time bearings are replaced and seldom get more than 2 years service before getting bearing noise. Trailer is pulled less than 2000 miles a year with less than 1000# gross weight on trailer. The only thing different from other bearings I've serviced is there is no washer between the axle nut and outer wheel bearing. What is the purpose of the washer? the axle nut is secured by a cotter pin. Is this washer necessary. The bearings, when inspected, still have lubricant. Am I missing something???