On the ML430, adjust as follows:

Remove wheel
get flashlight and look thru lug hole (on the left rear wheel, I believe just slghtly below or above the 3:00 position...on the right rear right around the 9:00 position)
You will see the star adjustment
whatever direction you move the star to tighten with a small screwdriver thru the lug hole, it will be the opposite for the other side
I bought Raybestos 777PG parking brake shoes for $30 (included $7 shipping). They were identical to the original MB with the exception of the 3 point star. IDENTICAL in every respect including all the numbers stamped into the metal parts.

A MB document I have says tighted the adjusting wheel until the brake shoes abut the parking brake drum and the rear wheel or the brake disk can no longer be turned completely freely by hand. Turn back the adjusting wheel until the ....can be turned completely freely by hand. When releasing the adjusting wheels, ensure the left and right adjusting wheels are turned back by the same numer of teeth (approx. 5 teeth).

Hope this helps.

__________________
Jim