ORIGINAL: Mr Ammo
I am leaning toward your idea of something loose in the 4 in 1...I have been all over this little chopper, and just do not understand...I just had a successful flight, although all my trims have changed, charging now to try it again and see if there is a repeat. Stands to reason, loose connection, bad solder joint..
The antenna situation is interesting, although I am not convinced this is a glitch from interferrence rather than a potentetial break in a circuit.
The main reason it sounds like a glitch is in order for it to just pop up and down instead of veer suddenly to one side or forward and back it would be a pitch change. Meaning a sudden signal impulse in all three servos. Even though it's worth checking, a bad solder joint would be unlikely to disconnect then reconnect constantly in flight. Either something is sticking somewhere or something is sending false signals.