For a disabled Comeng train, what must be done if the train is being pulled?

When a Comeng train is disabled and is being pulled, it is crucial to ensure that the train can be safely moved while managing its braking system. Setting the pilot valve and placing the reverser in the forward position allows for proper control over the train's propulsion system and ensures that the train can be moved as intended without inadvertently activating the brakes or causing other operational issues.

This action enables the train to be towed smoothly and safely, as it prepares the train's systems for movement. The pilot valve controls the flow of air to the brakes, and by placing the reverser in the forward position, it aligns the train's systems for the correct direction of travel. This step is essential to facilitate the towing process efficiently and safely while mitigating the risks associated with a disabled train.

The other options involve different aspects of train mechanics that are less pertinent to the immediate need for safely moving a disabled train. Isolating the static brake and conducting a pressure test may not address the immediate operational needs when towing, while increasing the brake pipe pressure might complicate the situation by potentially engaging the braking systems. Thus, the proper action when dealing with a disabled Comeng train being pulled centers around controlling the propulsion system effectively.