Coff,
I am sure someone far more knowledgeable than myself will be along soon.
It is not generally known that the hose was deployed by the use of the airflow around the rear of the a/c. I always understood the strakes were fitted to facilitate this. Once the paxolin doors had been opened (to allow the hose to traverse on the carriage) the small airflow shutter deployed and the hose brake released then the hose was free to extend. Sometimes when it was reluctant to do so the ALM would swing on the HDU frame and encourage it by 'pedalling' ! The hose would then be primed with fuel and it would adopt the stable refuelling position. All this while the HDU is attempting to pull the hose back in. This kept the hose rigid in the airflow. Should a customer spike the basket and panic thus removing the basket then the hose would rewind at high speed back onto the drum. Cue the rapid evacuation by the ALM to cower between the tanks .