Plastic window hardware that hold flat metal coil

One of my MI windows doesn't work properly. It is extremely difficult to pull the double hung window up and then get it seated properly when pushing down. I talked to a representative at MI and she recommended buying some new parts (since they no longer make this particular window and, as such, it is no longer warrantied). On the other windows this plastic piece seems to work well and you can remove the sash/pane easily. IMG_2721 is a picture of the plastic piece on a good window. On the problem window it looks like there's an internal rotating metal piece that isn't rotating properly. That may be the cause of the balkiness in moving the window. IMG_2722 is a picture of that same piece on the problem window. I do not see that particular plastic piece on this website. It is about 1-3/8" square and about 1/2" thick from what I can tell. Can someone tell me if this part is available and how to order it. Also, does what I'm surmising make sense? Is this the cause of the problem?