I am brand new to this boating stuff maybe someone can help. I have a 1965, Johnson, 75 hp, electric shift, outboard motor. On the lower unit about a half an inch south of the water intake, on the very bottom, is a tiny hole about 1/8 inch diameter. After I run the engine a small leak of cloudy, oily, watery substance drips out. Any idea why this hole is there and why is it dripping.