Simply, the brakes are adjusted at the drums, the bowden cable free movement is then checked and that the compensator in the middle is square to the pull rod. The brake effectiveness is then checked by use of the handbrake lever, ie, handbrake off no resistance,one notch and the brakes bind evenly both sides, lastly second notch should then lock the wheels.
Lastly you should then find the clearance between piston and actuating arm is minimal, ie, 2 to 3mm.
What you should never do is adjust slack in the brakes out by closing the gap between piston and actuator, unless it's the final adjustment having done the above correctly first
