Newbie here: I just bought a previously "built & tested" f450 w/gps, naza, gimbal, fpv. Came with spectrum rx but I have a futaba t8j so I replaced the rx w/ futaba 8ch rx. I have no response except that the gimbal works. NO throttle. rx lights up green the VU flashes (I think GPS error) and when I disconnect the gps from naza I still get an red/amber single flash. Ideas?