I have a 92 1500SE. End of riding season last year brake pedal started to get very soft. This spring installed new progressive springs in front and 416's on the rear. While apart changed pads front and rear and greased slider pins. Bled system from front to rear as aways, no air. Still no firmness to pedal. Since the bike is 20 years old the local dealership told be to install a rebuild kit in the rear master cylinder. Done that and bench bled the master cylinder and then the system. Still no firmness to pedal. Checked the thickness of the rotors and found them to be within limits. Checked all lines and fittings with no problems found. Had this bike for 9 years and do my own repair and maintenance and never had this much trouble with the brake system. What am I overlooking?