i got a 2003 mercury 15hp 2 stroke. its leaking alot of gear oil through the prop. it is brown color. i pulled the prop and their was fishing line behind it so is it my prop shaft seals? also i noticed there wasnt an o-ring in the back of the shaft. i already drained and refilled the LU. is there supposed to be a seal in front and behind the thrust washer? pics would help. thanks