It was this one, but essentially the same thing thing: http://www.amazon.com/gp/product/B00...00_i00_details

Cog is not backwards, the other way would make it further out of line.

Its bad enough you can feel the individual teeth engaging, the chain ring is visibly rubbing the inside of the chain on one side. Maybe it would be better with less chain tension? The pics I saw searching on here today often displayed visible slack where I thought it was supposed to be tighter than that.

I'll snap a pic as soon as I get back from the store.