As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CONSTANT REPORTS OF POOR BRAKES PROMPTED A REMOVAL AND INSPECTION OF MASTER CYLINDER. FOUND SIGNS OF CONTAMINATION BY REMAINS OF DISSOLVED RUBBER. REPLACED MASTER CYLINDER AND HOSES. SUBMITTER BELIEVES BRAKES WERE SERVICED WITH SOMETHING OTHER THAN WHAT IS SPECIFIED IN THE SERVICE MANUAL.