Where does the 2.5” spring and its gray roller govin this vacuum.

I took apart my shark and be 370- 26 To give it a thorough cleaning, and in the process a 2 1/2 inches long approximately quarter inch diameter spring that inserts into a gray plastic piece with a roller and the end fell out, and I am not sure where it came from or where to put it back. Can you help. I was looking for a parts diagram, but could not find one. YouTube videos are all about replacing filters, motors, and boards, and do not show this spring. Can you email me at dennis malkin@sbcglobal.net?