I have the exact same problem, it has nothing to do the the round blinking indicator light.. At start up, one of the motors runs a little slower than the others, and at idle the green "navigation light" blinks.. when additional power is supplied the light turns solid green just like the others.. If you listen closely, i believe you will here that motor oscillate slightly.. I have changed the motor with another one (used), and have the same problem.. i suspect that the motors or the bearings are creating resistance and at idle it is more obvious .. When it hits a "flat spot" it affects the light some how causing it to blink.. I have not flown mine with this condition, because I don't want to crash it again.. if anyone can help I'd appreciate it.. not sure if it's a motor problem or the corresponding electronic board which feeds the LED lights and the motor... thanks