a freind and i have had experience with the OFNA (older ones) failsafe and found something
with the fail safe installed, the throttle servo cannot be a high performance servo (mine was a Futaba 9450), or else it will glitch
then, he switched to a KO propo fail safe, and the glitching stopped
and i swithced to a pcm transmittor
but just to let you know, the older OFNA failsafes may have that problem