ORIGINAL: Shadow99
I've tried setting the neutral position on the rudder servo (an S9257), I thought I was in RATE MODE (rudder D/R set to 1).
The rudder dual rate switch does not control the gyro sensativity.
Your idle up switch will flip you from heading hold to rate mode.
ORIGINAL: Shadow99
The TX is set-up [GYRO SENS], RUDD D/R, RATE 0: 75% 1: 45% REV MIX: all zeros (unused), sub-trim 0 on RUDD, Travel Adjusts all 100%
From you setup it looks like you have normal mode setup for Heading Hold and idle up set for Rate. Power you heli on with the switch in normal or 0 position and wait for the light to turn solid red. Then switch to idle up, position 1, and your light should go out.
I hope this helps.