Improper thickness variation in the rotor

Repair or replace the rotor.

Scored rotor

Refinish the rotor surface or replace the rotor.

Excessive rotor lateral runout

Repair or replace the rotor.

Out-of-balance tire/wheel assembly or assemblies

Locate and repair out-of-balance tire and wheel assembly or assemblies.

Improper wheel nuts torque

Tighten the wheel nuts to specification.

Poor drum surface finish

Refinish the drum surface or replace the drum.