ORIGINAL: fizzwater2
I'm not a Futaba flyer, but it sounds like it might be too fast of a frame rate for the older analog servos.
Is there a selectable frame rate (high-speed mode, etc) that you can change?
I know my DX8 has 11mS or 22mS selectable, and the manual cautions that 11mS is only for use with digital servos. I'm pretty sure Futaba has something similar.
on the R6208, you can make it switch to a super fast mode, and this really send the servos nuts. So I have it back in "Normal".