Hydro-Gear Oil Leak
Roger, great pictures, excellent detail. If the O-ring replacement doesn't solve the problem,try this. With a blow gun clean off the pump, or better yet get a can of carb cleaner or gas and clean the pump. Take an Allen wrench and tighten the two screws that are on the top of the pump. It appears the oil is leaking out the top of the pump and not the by-pass. Start it up and you'll be able to see the oil leak on the clean, dry pump.