If you isolate the blow reeds you will find that its not too difficult to get them to sound when drawing on them.
The problem is choking the draw reeds. The draw reeds have to be set up very tightly in order for them to choke well.
Because of their smaller length to width ratio they have a greater tendency for torsional vibrations.
I usually need a lot of trial and error to get the high draw reeds set up well.
If the reed is set up well the overdraw is played exactly like any other overblow, from the back of the tongue. The tip of the tongue should be relaxed.
Again the important thing to remember is that the draw reed should stay choked, concentrate on that.
|Draw to choke to overdraw|