How are you guys doing this? I've found: http://youtu.be/eVdVa0jWowI and that's about it...which appears to work and I will give it a try, but I wanted to ask the community.... I emailed DJI and got a somewhat evasive response that repeated my question: "....they come pre-balanced from the factory." Yeah. I know that...How does one re-balance them? Thoughts? TIA..