scandinova df902 s/s?

Hi I have above cooker there is rattling noise coming from the rear,I switched off from the main and removed back panel and looks as though I have found problem but stumped how to fix it.
Will try my best to describe -above the fan there is for want of a better description a "roller" which is virtually enclosed it has come away at one end ,there is rubber type washer but try as I might I cannot get 2 to join up this is definetely were noise is coming from.
Any advice appreciated Tommy