Operating a hand push deck derusting machine typically involves the following steps:

Preparation: Before you begin, ensure that you have the appropriate safety gear, including gloves, safety glasses, and protective clothing. Also, make sure that the area you'll be working in is well-ventilated and free of any flammable materials.

Set up the machine: Install the brush or abrasive disk on the machine according to the manufacturer's instructions. Adjust the height and angle of the brush or disk to ensure that it makes contact with the deck surface.

Power on the machine: Plug in the machine and turn it on. Make sure that the brush or disk is rotating correctly and that there are no unusual noises or vibrations.

Start derusting: Begin by working on a small section of the deck at a time. Push the machine forward, applying firm pressure to the handle. Keep the machine moving steadily back and forth over the surface, using overlapping strokes to ensure that all areas are covered.

Clean the surface: After you have finished derusting a section, switch off the machine and use a vacuum cleaner or a brush to remove any loose rust or debris.

Repeat the process: Move on to the next section of the deck and repeat the derusting process until the entire surface is clean.

Final cleaning: Once you have finished derusting the entire surface, use a clean cloth or sponge to wipe down the deck with a rust inhibitor or other protective coating to prevent future rusting.