my zanussi just started making a lot of nosie that sounds a bit like the drum is coming off/apart. turned it off, turned drum by hand all o.k. will start in all cycles but with the noise. Checked filter found a small S/S nut & so called lock washer dont think it came from my clothes. How do you strip it down to check drum bearing? had the top off o.k. but the back does not come off.