Can anyone tell me how to properly manually adjust a 2002 trailblazer parking brake. THANKS!

Welcome to AF, must pull the rear rotors to get to the adjustment, then a special tool to gage how far to adjust, in lieu of that it is experimental as you must bring the adjustment out a little at a time till there is a slight drag on the rotor., also there is an update kit for the retaining clips on the shoes.