It sounds like the master cylinder rod attaching bolt is turned wrong. That bolt has a 3/4 head on one side and a 9/16(1/2?) head with a cotter key, on the other side. The bolt is made like a cam and you loosen the small nut and turn the big bolt until the brake pedal arm has about a 1/8 inch play, before it starts pressing on the master cylinder. What you describe is the master cylinder never fully releasing the fluid and after a few uses it has the brakes pumped up and won't let the fluid return to the master. Most people don't know that the bolt has the cam shoulder made on it.
