I thought I finally had my Sanwa Road Bike ready to ride, but a weird problem has arisen. Often, the chain will sit so only the edge of it is touching the cog, and it pretty much rotates freely around it. I have a 6-speed freewheel, the right chain, and friction shifters, and the cogs don't seem very worn, so I can't really think of anything that would be causing it. Here is my attempt at getting a picture of it. Any advice would be greatly appreciated.