A bearing that's failing will many times run at a elevated temperature compared to like bearings . You can check the temperature with your hand . Kill it after mowing a few minutes and compare the temp. of all like bearings .
With a extra vise a quick jig to hold a blade so the hand grinder can grind on the top edge . This blade gets about 30° and three 2 xs gives that angle close enough .
BTW , this is a original J D blade from a 350X and it's no harder to file than mild steel . So much for heat treatment .