[Alan Brinton]

This is almost certainly a matter of reed gapping, mudbone, with that particular reed needing to be opened up slightly. The difference may be visually noticeable when you open the melodica up and view the reeds from the side. The gap can be opened up (widened) easily by gently lifting the open end with a soft plastic toothpick and pulsing it up a few times and holding it up. Or you can slide a thin strip of cardboard from a business card or matchbook cover under the open end of the reed, down about 2/3 of the way to the base, and gently pry up a few times. You don’t want to overdo this. What you’re doing with the pulsating or holding up is to create a new “set point” that has the open end of the reed separated a bit more than it was from the reed plate. But you don’t want to create a noticeable bend in the middle of the reed. Just do it a tiny bit and then repeat if necessary to get it where you want it. This is a less common problem with a Suzuki than with a Yamaha, and the problem is less likely to recur.