Take out some strong wood glue and dab a little bit in the blank spots where you haven't carved anything and put a LITTLE LITTLE bit on the stem because when you put the two halves together, the glue will want to seep into the airway and block it up. Clamp the two halves together or put them in a vice for a few hours. Once it is completely dry, take it out of all the pressure and blow pretty hard into it. If you could blow through, then you're ready to move on. If not, then place the tip of a flathead screwdriver on the seam where the halves met and tap the top of the screwdriver with a hammer to split them apart. Sand all the glue off and carve the airway a little deeper, and then try to glue them together again.