Vacuum runs briefly, then stops and shows E3; brush roll in the motorized head does not spin.

Safety first: Turn off the vacuum and remove the battery pack. Never work on the brush head while it is powered.

• Remove the brush roll: On most Hitachi cordless heads, open the side cover or release latch and slide the brush roll out. Note the orientation for reassembly.
• Clear entanglements: Use scissors to carefully cut away hair, threads, and fibers from the brush bristles and end caps. Avoid cutting the bristles themselves.
• Check brush bearings: Rotate both ends of the brush roll by hand. They should spin freely. If they feel rough, seized, or melted, the brush roll assembly should be replaced.
• Inspect the brush motor area: Look inside the nozzle where the brush roll sits. Remove any debris around the drive gear or belt (if used). Ensure the drive gear turns by hand with slight resistance.
• Reassemble and test: Reinstall the brush roll, ensuring it is fully seated and the cover is locked. Refit the battery and test. If E3 returns immediately and the brush does not move, the brush motor or wiring harness in the nozzle may be defective.

Persistent E3 with a clean, freely spinning brush roll usually indicates a failed brush motor or internal wiring in the motorized floor nozzle, which may require replacing the entire nozzle assembly.