Other Sounds to try.
Trill Tongue
A great sound is trilling your tongue like the /rr/ is pronounced in Spanish.
Combine this with various calls.
Make up your own sounds
*Truck backing up - Medium high pitched even tones.
*Talk through call - “Hello, how are you?”
Try not to spit while blowing!
Troubleshooting: If call gets real wet to the point of not playing it is easy to fix. The plastic reed can get temporarily stuck to the bamboo. This will not hurt the call. Blow air hard from side near the tied end toward the middle. This will bring the reed back to the center of the call.