Unable to locate oil leak on 8hp 2 stroke Mercury

[Skidude17]

The motor is a 1995 2 stroke 8 hp Mercury SN: 0G765923 . I got this motor as a kicker on a boat I bought last year. When I changed the oil for wintering last year, I saw a very trace amount of water in the gear oil, but during pressure tests it maintains pressure, so I thought it must be because the previous owner had double gaskets on both the drain and vent plugs. After running the motor for about 4 hours recently, I found oil coming out of the gear casing behind and through the prop. I drained the gear oil, and there was more contaminated oil then when I winterized it. I’ve pressure tested the gear case again, and it is very slowly losing pressure. I can’t find the source using soapy water. I’ve tried around the prop shaft seals, around the water pump, around the drain plug, and around my pressure tool on both ends of the hose with no success. When I dropped the lower unit, I found a bunch of contaminated oil in the exhaust cavity of the lower unit seen in the attached photos. I don’t want to change seals that are still good. Does anybody have suggestions for other ways to test or locate the leak?
Thanks!

 

[GA_Boater]

The oil in the exhaust cavity is normal and caused by trolling.

Two ways to find the leak;

1. While pressurized and spraying the soap/water mix rotate the prop shaft, shift shaft and driveshaft. Some seals only leak while turning.
2. Pressurize and dunk the lower unit completely into a tank of water and look for bubbles. Again rotate the shafts.