I have a 1966 Evinrude Starflite that has an obvious leak in a least one lower unit seal. Bought this from a guy that had not used it for two seasons. He said the LU had a "minor leak". Did a drain and fill of the LU with type C, and it clearly has water intrusion and its not minor. I took it to a boat ramp to do some test runs. Engine coughed and wheezed but it is running great now. I put it into gear and after about 10 minutes the engine labored while in gear and shifted very hard. I immediately shut it down, and inspected the LU fluid. Very milky. So now I need to reseal. Is this a job for a novice or best left to a pro? I love to boat- its a 1966 Glasspar with a great look to it, and the engine while old really adds to its classic appearance, so if possible I'd like to make it work.