[Harp-L] Blow Choking on a Special 20

[Tony Renshaw <tonyrenshaw268@xxxxxxxxxxxxxxx>]

I have a Special 20 in the key of C that won't allow me to ascend it 
quickly without choking. To start on the 1 hole blow and rise quickly to 
the 6 hole blow, with anything but light pressure and volume, results in 
choking of the intermediate notes. It doesn't sound crescendo like at all. 
I have another, or in fact several other Special 20's in C, new ones, but 
this one is unique. Is this a common symptom, or at least one I can expect 
over time? Why does it happen?
Reg
Tony Renshaw
Sydney Australia