I'm putting new back to back seals in the driveshaft bearing housing when i notice a small hole that (I'm guessing here) carries oil to the bearings inside the housing? If so, then why does the first seal i install effectively cover it up ? How does the oil get to the bearings? Also, does the orientation of the hole, with respect to the lower unit, make a difference? i.e. does the hole face forward or backwards towards the prop? Thanks in advance.