It all started when my Hoover suddenly turned off for the first time after about 5 minutes of normal carpet cleaning. A little googling revealed that the Hoover thermal protector worked due to 3 common problems: a clogged hose, a dirty washable filter, or a HEPA filter. I checked the first two. You were fine. The HEPA filter looked dirty and was never changed. Replacing the Green Label filter fixed the problem. It fits and snaps in well. It's firmly in place and won't come loose on its own. The most amazing thing is that the vacuum cleaner picks up dirt like new. He was collecting a lot of dirt after vacuuming with an old filter a few days earlier. Highly recommended.