Most of the inexpensive choppers are contra-rotating, they have two main rotors that spin in opposite directions, and are really stable and easy to control. Changing the speed of the two rotors makes the bird yaw, rotor speed controls lift, and there's a conventional swash plate for pitch, which is the only servo needed.
Wow...if that last sentence is true, it's an amazing oversight on the part of the manufacturer. All of the controllers would potentially have this problem. And most of them -- at least the ones not sold to a mechanical engineer -- would have to be replaced.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.