It can be very frustrating. You pull out your favorite harp and start to play and nothing comes out. Not sure what's going on, you blow or draw harder and still nothing. We call that "choking". It is that point where you feel like you are trying to blow up a balloon and there is no movement of air and no sound.
For the reed to vibrate, it has to have free flowing air on all open sides. However, the closer a reed sits to the plate, the more efficient the reed functions. In other words, it will go into motion producing a cleaner and more pure tone if the reed has just enough air to set it into motion, but excess air is not passing by the reed.
If we are seeking to be an advanced player with smooth bends and a clear tone, we want the reed to be set as close to the plate as possible. However, moisture from our breath, environmental factors, and dried saliva will occasionally take up the air space in between the reed and the plate. This will cause the reed to choke. Also, quite frequently players will develop a habit of playing with more force and that will contribute some to a choking reed.
Whatever the cause, the choking reed is a source of frustration for players but there is a very simple fix for it. The videos below will demonstrate some quick and easy techniques for adjusting Seydel diatonic reeds. Develop this skill and you will be able to make micro-adjustments to your diatonic harmonicas to suit your playing style and preference.