Hombre,
Like Pat says you want a bit of free play in the pedal on a power brake pedal. My approach is at rest you should be able to pick up the pedal just a bit, pulling the pushrod away from the diaphragm to be sure that there is no pressure on the diaphragm, which is a little different than freeplay on a clutch. Some are threaded to adjust, or shims like Pat says, or even grind down the pushrod to gain some clearance.