Thanks. I got the service manual in PDF format so will be looking at that. I also subscribed to the Kohler Yahoo! group and await a reply from them. My only hope is that I don't have to spend lots of money on custom tools to do this job. Fingers crossed.
Edit
http://www.bodoin.com/images.oil_leak2.jpg
The new photo shows what it looks like without the flywheel cover attached. The red circle indicates an area of pooled oil that cannot be clearly seen because of the shadows.
Another Edit:
Argh! there's a hole in my engine, my engine, my engine, there's a hole in my engine, what shall I do?
http://www.bodoin.com/images.oil_leak3.jpg
The hole circled and arrowed in this new pic shows a little hole and even though I probably shouldn't, when I run the engine I can see oil coming out of it. I am going to contact Kohler and see if:
1. it's a defect,
2. it's a missing grommet or something,
3. they will replace my engine (like the Mass lemon law with cars kinda thing),
4. can I fix it with something