I never understood how people said words to make the sounds. Never worked for me. That whole "chalk" thing, bogus. I just listened to the turkeys and mimicked their sounds with the call.

As for purring...

Can you make the motor boat sound with your lips? Vibrate your lips together? Put pressure on the call and vibrate your lips together. It takes a bit more practice than the other calls, but once you get it down you're golden.