When testing the operation of all compartment doors during PDI, what action should be taken as necessary?

The correct action during a Pre-Delivery Inspection (PDI) for testing the operation of all compartment doors is to lubricate them. Proper lubrication ensures that doors operate smoothly and do not stick or jam, which can occur due to rust, dirt accumulation, or other forms of wear. Regular maintenance through lubrication prolongs the life of the moving parts of the door and enhances the overall operational efficiency of the compartment doors.

While repainting the doors, replacing the handles, or securing the locks may be actions that could be necessary under different circumstances, they do not directly address the immediate operational testing of door functionality during the inspection process. Lubrication directly impacts the functionality and usability of the doors, making it the most appropriate choice in this context.