Once you come off of the low idle position, and the motor is spinning, the break is no longer active. The brake isn't proportional to the throttle. Once you come off of the brake it is on. To take advantage of the brake, the motor must be able to reach the low throttle position. Some people use various conditions to create a low idle for stall turns and such, but you have to allow full low throttle position to be available to activate the brake,

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