I had same problem as you with heli droping. Motor connector on negative side just fell off when I removed shrink tubing. I replaced all connectors that fit more snug and made sure my solder job was good and the heli performs much better. I also re-routed all of my wires. All radio/servo wires run on the right side of frame and all battery/motor wires run on left side of frame. Kept radio and power wires as far apart as possible. With the Hitec HS-55 servos and Blade CP paddles with 1/16" wheel collars halfway out on flybar and putting rotor head on high point balancer to get as perfect a balance as I can, the machine flys best it ever has. My next step is a GY240 gyro.