It’s summer. It’s hot. Your big ol’ box fan is ailing. Time to
buy a new fan CLEAN IT!
After only one season a fan may be covered in enough gunk to give the illusion that the ‘motor’ is worn out, when really all that is needed is a good cleaning to keep it running for a lot more hours. I have often picked these up on trash day, and gotten years of use from them. Rarely I may have to replace a knob, but usually they are functioning, but the blade speed is about half of normal.
I do this every season to my own fans and these $20 box fans last a lot longer then the manufacturers want them too.