Block the front wheels, then jack up the rear of the vehicle and support it securely on jackstands. For a quick check, the thickness of friction material remaining on one of the brake shoes can be observed through the hole in the brake backing plate by prying out the sealing grommet. Remove the rubber plug and check the brake lining thickness through the backing plate aperture. If a rod of the same diameter as the specified minimum friction material thickness is placed against the shoe friction material, the amount of wear can be assessed, and a flashlight or inspection light will probably be required. If the friction material on any shoe is worn down to the specified minimum thickness or less, all four shoes must be replaced as a set. For a comprehensive check, the brake drum should be removed and cleaned, allowing for the wheel cylinders to be checked and the condition of the brake drum itself to be fully examined.