To confirm the top seal is leaking, you can pour some TCW oil or fuel mix on it and crank the motor over with a socket. This has to be done with the mag plate removed. Removing the spark plugs will make it easier to crank it over to.
https://www.youtube.com/watch?v=cXt6fV6Z5rc
You can remove the seal if you don’t have the proper tool or don’t want to split the cases. Punching or drilling some holes in the seal will let you get some screws threaded into it which can then be used to work it out. The bearing is right below the seal so you want to make sure you get any metal chips out before installing the new seal.
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