Guys,
I found that when riding my 2004 Sportsman for a bit I heard what sounded like air coming out or oil coming out of the bottom of my motor. I got down and looked and didn't see any coming out, but found oil on the bottom of the motor. I pulled the rope out of the crankcase and found oil all over it. I checked breather hose and it's not clogged. Any help would be appreciated. I'm thinking crankcase seal? Much appreciated on any info and is this hard to fix if so?

thanks
Nate