After locking out a machine, what is a crucial verification step?

Pressing the start button to confirm that the machine is truly off serves as a crucial verification step after locking it out. This action directly tests whether the lockout procedure has been effective by attempting to activate the machine. If the machine does not start, it indicates that the lockout has worked properly, ensuring that it is safe for maintenance or repair work. This practice is part of the lockout/tagout safety procedure, which aims to prevent accidental machine start-up and protect employees from potential hazards.

In contrast, while checking with a coworker, inspecting the surroundings, and disengaging all controls are important safety practices, they do not specifically validate the effectiveness of the lockout. Verifying the machine's condition through direct action allows workers to confirm that all safety protocols have been successfully implemented before proceeding with any work.