how to identify part in a eureka 4870F?

I can see that the flat tension (spring-for lack of a better word) that comes from under the steel belt wheel at front end of belt assembly is broken. It flops around and does not provide added tension needed to make belt be the correct tension to spin the beater bar. I cannot find what the exact name of the piece is or any picture of it on the web schematics of this model. Can this be changed out or is a part of a bigger assembly unit and therefore a the whole steel wheel assembly must be changed?