Gimbal SimpleBGC Setup

Hello. I have a problem - my gimbal om SBGC working strange - gimabal come back to 0 position in mavlink tar and rc tar mode. i know about parametr MNT1_RC_override, but if they have value >0 gimbal do not move. I need make - when i turn tumbler up they go up, down - down, but in midle it must stop , not turn to zero position. Thanks