I'm using a 14SG radio and have a throttle servo on channel 3 controlled by J3 and a servo on channel 8 (VPP) controlled by switch SG (Off/On/On). The channel 7 servo arm positions correctly via switch SG at 90 deg apart (i.e. off position (vertical) and on position (horizontal) are as desired.) I want to mix the throttle channel with channel 7 such that at low throttle, the channel 7 servo moves to the on position (horizontal) and above low throttle the channel 7 servo moves to the off position (vertical).

Essentially, I want the channel 7 servo to be in the off position whenever the throttle is high AND SG is off and the channel 7 servo to be in the on position whenever the throttle is low OR SG is on.

My attempts so far result in J3 not moving the channel 7 servo enough (even at OFFS Y at -100) and it adding to the channel 7 servo position. That is, SG off and J3 low only moves the servo about 45 deg instead of 90 deg and SG on and J3 low moves the servo about 135 deg instead of 90 deg.