Got some good news and some bad news.
The good news is that the problem is an "O" ring around the shaft. Replace the "O" ring, problem solved. Now for the bad news.
I looked in the manual and they show that to replace the "O" ring you have to open up the case. Working inside the case, you remove the shaft, a bushing and the seal, reverse to install. That's the manual, in real life it would be nice if you can use a pick tool to pry out the old and then push a new in its place. If anybody has done it, tell us.