In the attached photo, you can see a "wet" bolt head on the front-left of my Yanmar 1401D. This is leaking a very small amount of gear oil. Can someone explain to me how to fix this? Thanks for your help.
It's hard to tell from here if the leak is from the bolt or the flange. clean it off and determine. If it's the bolt head, remove it, clean, and coat the threads liberally with silicone sealant and re-install.