The Gapping Paradox
The gapping paradox is a reed that doesn't respond unless it is very tightly gapped or a reed that locks up unless the gap is opened too much. It's either all or nothing. In both cases, the instrument is no fun to play no matter how you set the gaps. The Gapping Paradox is also the expectation that the only setup a harmonica needs is gapping.
Sometimes gapping doesn't work.
Gapping is adjusting the height of the tip of the reed at rest.
The height from the reed plate determines how much breath it will take to get the reed to play.
Best practice is to adjust the gaps so that the reeds all respond to the same breath. If the instrument offers you enough range, you can fine-tune the reeds to best suit your breath force habits too. Some players prefer harps to respond best to hard breath and some prefer harps that play with less air.
There is an expectation among harmonica players that the only setup skill you need to learn is to gap a harp "to your preference".
We all know this is false. There are times when you can't get the reeds to respond unless the gaps are way too tight - so tight they are not playable. And if you open up the gap even a little bit, the note becomes sluggish or plays with too little power and bad tone.
Likewise, we see reeds that lock up unless the gaps are opened up far too wide which makes both the blow and draw notes too airy and very weak.
This is the gapping paradox: It's either all or nothing.
When faced with this paradox, most harmonica players come to one of two conclusions:
1 - "It's my fault, I'm terrible at gapping. There is some secret extra skill to gapping that I just can't tap into."
2 - "This harmonica is a dud. There is nothing anyone can do about it."
Usually, both conclusions are false.
When you run into the Gapping Paradox, understand that to fix the problem you need to go beyond gapping.
It's the harp's fault. It is a victim of mass-production syndrome. It's not possible for a factory to churn out perfectly-adjusted defect-free instruments unless hours of work are spent on each one. But it doesn't mean the harp is a dud, either.
In most cases, the defect(s) can be corrected in a matter of minutes.
Foundational problems include warped or bowed reed plates and combs. Another foundational problem is a reed that's off-center at the base.
Bowed reed plates are particularly sneaky! In addition to making the harp leaky, you can be fooled by gaps that seem to change all by themselves.
You can adjust the gaps to your liking with the covers off only to find that the harp is completely reconfigured every time you put on the covers. This is because the covers are changing the shape of the slots as the screws are tightened. You are putting tension on the bow.
A bowed reed plate can also make you think there is a problem with the reeds' shape. (See below.) But the problem is that the slot is not a straight reference (it's bowed!) Always address foundational problems before you consider reed work or you will be working against yourself.
Gaskets can help relieve air leaks but they don't make the slots straight. The best solution is to straighten all components.
With a little practice, you can correct the flatness of most combs and both reed plates in a matter of minutes. I offer tools to help with this which allow you to see the curvature and fix it.
Off-center reeds can be aligned at the base. See here.
Reed shape problems are another common cause of the Gapping Paradox.
Gapping focuses on the very tip of the reed. "The gap" is the height of the tip of the reed by definition. Think of reed work as gapping the whole length of the reed. We are adjusting the height of every part of the reed from base to tip.
For example, if the middle of the reed enters the slot before the rest of the reed, there is no amount of gapping that can make that reed perform well. This reed will always disappoint you until you fix its shape.
You can find more details about reed work in the second half of The Grip video and on my USB videos
Again, with a little practice you will be able to fix obvious problems with reed shape in a matter or minutes. This will turn that dud harmonica into a fully-functional part of your collection.
You can do it! A little bit of knowledge and an afternoon of practice can make all your harps play better, save you money (don't throw away a dud) and give you more confidence.