This is the hardest leak to fix. The main cause of this leak is wear in the main drive gear bushing, which goes between the main drive gear & the main shaft. Wear in the bushing allows the Main Drive Gear to `wobble` slightly on the mainshaft, making any attempts to seal it doomed to failure eventually. It is rather easy to re machine the mainshaft to accept a 5 speed bearing, eliminating the bushing and the cause of the leak.

 

Thank you gents.

 

At the shovelhead.usa technical forum I came across a replacement main seal being machined by one of the members there and most say it is a pretty good cure for the leaky seal. I wish I had found it before I replaced the one on my shovel. When this one starts leaking I will do just that.
There is a pretty good thread in this forum concerning dependability updates for shovels. I would recommend reading it. Some are cheap. Some are just labor and some are a bit pricey.
My shovel is pretty tight. I have a leak near my clutch release lever I need to resolve, but that's about it. And all shovels will likely leak at the crankcase vent. Do not put a filter or any other obstruction on that one. Will end up building up pressure and you will get leaks elsewhere.