I got two harps and played them. Each had a small leak that seemed impossible to get rid of. I placed the plates on a very flat surface and placed a light behind them. Most were slightly bent and I very lightly rubbed them in a circular motion. Reeds up. to see if the plates were correct. I could see where a portion of each plate did not show any sign of contact. I have the straightening claws and got them closer. Rubbed again clockwise and counter clockwise with no significant pressure. I only want to see if part of the plates are not showing any contact. After getting them correct, no light showing from behind I put the cover plates on and it made a significant difference.
The right side of the harps is so much easier to play with little air. I doubt there are many factory made plates, out of the box, that were not custom made that are right.
This is one of the first things that most harp customizers do: sanding the draw plate to make it flat. The blow plate you can skip because the side without the reeds does not contact the comb anyway. With a harp made like the Hohner Marine Band, Seydel 1847, Suzuki Manji and others with that so-called “sandwich” construction, you should also sand both sides of the comb to be sure that it seals as well as possible with the reed plates. There are various YouTube videos demonstrating how to do this.
An alternate approach used by some customizers is to use a sort of gasket that is inserted between the reed plates and the comb and can seal air leaks.
Simply because a comb might be made from ABS, brass or any other metal does not automatically mean that its surfaces are flat and it is only the reed plates that are responsible for air leaks.
You nailed it. Biggest problem is finding a flush surface. I disliked my Marine band until a plastic comb and the reed plates were corrected. can bowed out of the box.
