The side brushes and filters were mostly fine. You could say that the stiffness has decreased, but in general it was acceptable. What made me write a negative review is the main brush failure. The main brush bearing is completely stuck. This tells me that replacement brushes will most likely use lower quality bearings and have much tighter tolerances. In comparison, my original brush, which I've been using in the same conditions for over a year, still spins well. I have two long haired dogs, so my cleaning conditions are much worse than without pets.