Do you mean that the key gets stuck in the down position? Or do you mean that you get no sound? Is there a strip of felt along the front of the keys? If so, is there a concentration of moisture in the felt at that key? Some of us have occasional problems with a key not playing on our Yamahas, and there has been discussion about how that may relate to a concentration of moisture and/or to gapping of the reed. But it sounds like you’re saying that the key itself is getting stuck. Is it something you can “play through” without opening the instrument by varying the wind pressure and alternately blowing and sucking? I’m able to do this with my Yamaha keys.