I have a crasshoppoer 725D that has a grease zert on the drive shaft about middle way under mower. I bought the thing new and it has 500 hrs on it. The salesman showed me the zerts I needed to keep greased and did not mention this one. I don't recall the owners manual mentioning this zert I'm talking about. I used a 3 ton jack to jack it up as it is heavy. Still could not get to it. How long can I expect this bearing to last without greasing it? Thanks