I've got an oil leak comming from behind the front sprocket... or the shifter. Its so messy, I tried to wipe it up and ride to see where it was comming from but its just all over, so I'm going to replace both of them. Has anyone done this? What am I getting myself into? How do you get that old seal out? hook it and pull or ?? And how will I get the new one in (hopeing I can find a replacement part today...) wihtout bending it all up? Any hints, tricks, tips, would be great.