Howdy, I also have a Consew 206 that I bought used that came with a lot of cool extras. Mostly old cowboy carttridges for selling belt loops.
You can contact
Bob Kovar at Toledo Industrial Sewing Machines, and he can fix you right up with the speed reducers. He can also fix you up with thread, needles, roller guides, and presser feet.
Others to you can contact are
http://www.leathermachineco.com/ - Cobra Steve
http://www.neelsaddlery.com/index.html - Ryan Neel ( I believe that is his name).
All of those guys are full service leather machine dealers who know what they are talking about. Local sewing supply places typically don't know anything about sewing leather.