Try buying a thing of Natures Miracle and soaking the lead in it for an hour or so, then rinsing it out. Natures Miracle is made for people to get the pee smell out of carpets when their house pets have accidents. You can get it at most big pet stores and some grocery stores. Here's a link so you can see what it is:
Nature's Miracle - Home.
If you want to go the cheap route, try the same thing in a bowl of white vinegar. (Of course, then you'll have a vinegar smell, but washing it in something else afterward should cancel out the worst of it.)
Don't use anything ammonia based....that will just make it worse.