Please don't take this as critical, but Lionel O gauge is like a Ford or a Chevy: any shop in town should be able to work on them and have/get parts. If you're in a hurry to get it working, find a local hobby shop that works on Lionels and take it to them. They should be able to fix it quickly.
On the other hand, if you're a hands-on guy, get on the web and try something like "repair smoke Lionel train". Here's what I got on the first try: http://ctt.trains.com/en/Collecting/...e%20units.aspx
THe Lionel O gauge guys here are pretty good, so I expect you'll find additional advice soon. Best wishes!