A vacuum cleaner’s switch may need to be replaced when it starts to malfunction or show signs of wear. Common indicators include the vacuum not turning on or off properly, intermittent operation, or the switch feeling loose or damaged. In some cases, the vacuum may only work if the switch is held in a specific position, or there could be a burning smell or sparking, indicating electrical failure. Additionally, in models with electronic or touch-sensitive buttons, an unresponsive switch may also require replacement. If any of these issues arise, it’s important to address them promptly to ensure safe and reliable operation.