I dropped my 1975 Johnson 25, 2 stroke into the test tank after replacing the plugs and spraying de-carb in the carb. When I fired it up, it ran like a top. After the test I noticed an unusual amout of oil in the test tank. Could I be leaking lower unit oil somehow? I mixed my oil/fuel a little lean according to directions @ about 30%. How many seals are there in the lower unit that I would have to replace?