Yes, there is a very expensive, special high quality seal on this shaft. The seal consists of two high precision lapped and spring loaded plates, running face to face. The O rings in the seal do not seal the rotating shafts, just prevent leakage around the seals. Cats have the same sort of "Duo Cone" seals in their track rollers. Few combine operators will tackle a seal replacement, prefering to leave it to a competent mechanic. It can and has been be done in the field without draining the Hydro oil in an emergency by one of our local mechanics on a number of occasions. It is not a very difficult job. Just read the relevant part of the manual thoroughly and understand how the seal works. Warning! The seal has multitudes of springs and bits! If it falls_ flies apart you may be chasing bits around the floor for quite a long time. Any visitors that drop in will be suitably impressed with your masterful use of the worst aspects of the english language! Drain the hydro oil. Remove the belt pulley off the tapered shaft. Clean thoroughly as any dirt can be fatal to the high precision seal faces. Carefully dismantle and withdraw the old seal. Clean inside of the seal cavity thoroughly as dirt works it's way into the seal cavity and eventually damages the seal faces. Install new seal and it's accompaning O rings. We placed a disc slinger onto the shaft to cover the seal cavity and to restrict and prevent dirt ingress into the cavity before reinstalling the pulley. Don't get concerned with some slow weepage from this seal. Just keep an eye on it and check the hydro oil level regularly. Cheers!