Which of the following is a sign that equipment may need maintenance?

Unusual noises are a significant indicator that equipment may require maintenance. When machinery operates correctly, it typically produces consistent sounds associated with its normal functioning. However, deviations from this sound pattern—such as grinding, squeaking, or clunking noises—can signify mechanical issues, misalignments, or worn components. These sounds often suggest that internal parts may be failing or that maintenance is needed to prevent further damage or malfunction.

The other options do not indicate a need for maintenance. Regularly scheduled use suggests that the equipment is in operation as intended and might not inherently signal any maintenance needs. Normal functioning indicates that the equipment is performing as it should, without any signs of issues. Lastly, having all parts accounted for suggests completeness but does not reflect the operational state or signs that would necessitate maintenance.