Final answer:
Technician A is correct about adjusting the service brakes before the parking brake. Technician B is correct about cleaning the threads of the adjusting nut.
Step-by-step explanation:
Technician A is correct. The service brakes should be adjusted before adjusting the parking brake. The service brakes are responsible for slowing or stopping the vehicle during normal driving conditions, while the parking brake is used to keep the vehicle stationary when parked.
Technician B's statement about cleaning the threads of the adjusting nut before adjusting the parking brake is also correct. Cleaning the threads helps ensure smooth and accurate adjustment of the parking brake system.