This seems to confirm what I was just saying about the base of the reed:
Playing loud is the #1 killer of harmonicas.
Each reed is a spring… a spring that travels in and out of the reed slot 880 times per second for a 7+ on your A Harmonica (1,760 for the 10+!). When playing louder, the reed doesn’t travel faster (faster vibration equals a different pitch), it travels farther. The louder you play, the farther the reed travels in its arc and places stress on the base of the reed (this is where a reed breaks… right at the hinge… near the rivet).