Flying my BCX indoors, and I am noticing my heli goes forward. I am not able to get the heli to go backwards. I play around with the adjustments on the transmitter (trim), but nothing changes, thinking it is the heli. I have changed the upper rotor head and inner shaft 3x along with the stabilizer Flybar 2x in the past due to incidents (outdoors). How do I adjust the Elevator Trimming on the Blade CX (not the transmitter)?