Assuming we're talking about an outboard, could be a couple/few seals that need replaced. Do you have two bolts behind your prop (top/bottom)? If so, that's the bearing carrier. If it's not a saltwater boat, you should be able to free that up and pull it out. Lots of videos on youtube for the process. Seconding, once out, you'll see the first of the oil seals; it will be stainless and have writing on it. A seal puller probably won't work. I just went through this process. What I did was copy information from a YouTuber called "born again boating". He's got a plethora of great information on his page. He showed me how to very carefully drill into the outer seal and use drywall screws and flat bars to remove it. Once that's out, the other one is just rubber and will come out much easier. It's really not that hard to do. Watch the videos. Find the correct parts and order them and have at it.
In my case, I couldn't get any help for what would've turned out to be weeks so I just jumped in with both feet. If I can do, so can you. In my case, I'm a Saltwater guy so there was no way to get the bearing carrier off. I had no choice but to change the seals with the prop shaft still in place. You just have to be extra careful because you cannot scratch/nick/damage that shaft. Make sure you have good, sharp drill bits.
