You gotta pick the brake, and slide about a .003" feeler gauge in between the brake drum and shoe, all around at every point. Best to get really long feeler gauges from a specialty hardware store. You need long feelers, to get in the backside. Adjust the four black bolts, until the shoe is even all around. (those are the four bolts with the little sheetmetal locking plates)
When you finish with the e-brake, swap the power and switch cable on the power supply, (5 wire cable), and do the main brake. Put the cables back when done.
Screw the brake switch adjustment cw until it clicks, (bk de-energized), then ccw until it clicks out. Make sure the emergency release cable isn't tight. The washers on the center bolt should be free to spin.