What do you mean by won`t lock? Is it drifting when you`re hovering/flying? Does it bounce back after a hard stop? Is it swinging on a hard climb out or hard collective change? We need a little more information to be able to accurately help you.
I'm with Geena, we will need more information. Just from what I read, my brain is saying the gain is not set like there is no tail gyro. But again, we need more information to accurately diagnose what is happening.
