A burr is on the lock bolt.

1. Inspect the lock bolt.
2. Replace the lock bolt. Refer to Steering Column Tilt Head Housing - Disassemble - Off Vehicle or Steering Column Tilt Head Housing - Assemble - Off Vehicle .

The ignition switch is damaged.

1. Inspect the ignition switch.
2. Replace the ignition switch. Refer to Ignition Switch Replacement - On Vehicle .

The lock cylinder is damaged.

Inspect the lock cylinder.

Replace the lock cylinder. Refer to Ignition Lock Cylinder Replacement - On Vehicle .

The ignition key is worn or damaged

Replace the ignition key.