What is the major contributor for mechanical washer failure?

The correct answer highlights that improper loading of instruments is a significant factor in the failure of mechanical washers. When instruments are not loaded correctly, it can prevent optimal cleaning due to limited water flow and poor exposure to detergents. Proper loading is crucial for ensuring that all surfaces of the instruments receive thorough cleaning, as densely packed instruments can lead to obstruction, trapping debris and contaminants. This not only affects the effectiveness of the washer but can also compromise the sterilization process, ultimately leading to patient safety issues.

While the other choices may also contribute to mechanical washer failures, the emphasis on loading speaks to a common practice issue that can easily be addressed through proper training and adherence to loading guidelines. Thus, ensuring that instruments are loaded according to specified protocols is vital for maintaining the efficiency and effectiveness of the cleaning process in sterile processing.