My issue turned out to be a little different because I originally blamed the belt every time the mower started leaving uneven patches. After taking a closer look, I found the blades were just as worn as the belt, so replacing only one part never solved the problem for long. That's when I started following the advice to buy blades here, and since replacing both at the same time, my mower has been running through two full seasons with far fewer problems and much more consistent cutting.