Mower vibrates excessively, especially when the cutting system is running.

Safety first: Press STOP, switch OFF, and remove the key before turning the mower over.

• Check blade count: Ensure all blade positions on the disc are filled with blades and screws.
• Inspect for bending: Spin the disc by hand and watch for wobble. Replace the disc if bent.
• Clean disc: Remove any clumps of grass or dirt stuck to one side of the disc.
• Replace blades as a set: Always replace all blades at once to maintain balance.

Persistent vibration after these steps may indicate a damaged motor shaft requiring motor replacement.