Dell 3120cn roller - how to reseat?

Hi,

Hope someone can help.

I had a paperjam on my Dell 3120 and when I opened the front to remove a roller came out (not sure if it was attached to printer or fuser or ....)    I can't see how and where to reconnect it.   It's about 9" long, maybe 1/4" circular, black in colour, with a black cog at one end (maybe 1" diameter) and 4 rollers along it.  The other end to the cog is round.   Without it the prninter prints but jams most of the time.  If anyone has one of these printers and could see where it goes that would be a huge help.

Thanks

Paul