Don't part it out, that would be stupid. I do agree with getting it cleaned up. Start with some Simple Green that you can get at Home Depot and clean all the oil and grease off everywhere you can see.

Once it's cleaned up, you can make a judgment on what needs to be done next. You can remove the front sprocket easily enough. Make sure you leave the rear wheel on the bike and the chain installed while trying to get the bolt off that holds the front sprocket on. You can put a 2x4 through the spokes of the rear wheel while getting the bolt loose on the front sprocket. It's a standard "righty tighty, lefty loosy" bolt on that sprocket. Once you have the bolt off, you can then remove the rear wheel and there is plenty of slack in the chain to be able to get the front sprocket off without having to break it.

Oh yea, I forgot to mention. I couldn't find anywhere in the manual that talks about that seal. I guess you'll have to get it cleaned up and the sprocket removed before you can determine what the cause is. After it's clean, but before you take it apart, take it for a ride so you can attempt to see if oil is leaking somewhere. I hope it's not that the PO just used motor oil to lubricate the chain and that's the mess it caused.

Let us know how it goes. Those are great photo's BTW, so keep'em coming.