CURRENTLY OWN 1986 BUICK ESTATE EQUIPPED WITH "POWER MASTER" BRAKE UNIT. THIS IS THE ORIGINAL FACTORY BRAKE UNIT FOR THIS AUTOMOBILE. THE PRESSURE SWITCH DEVELOPED A CRACK, ALLOWING THE BRAKE FLUID TO BE PUMPED OUT. MY FATHER WAS DRIVING THE VEHICLE AT THE TIME, AND MANAGED TO GET THE CAR STOPPED AND OFF THE ROAD WITHOUT CRASHING. NEVERTHELESS, THE RESULTS COULD HAVE BEEN MUCH DIFFERENT. WHAT'S MORE, I KNOW NOW THAT GM HAS LONG BEEN AWARE OF THIS DEFECT. SINCE THIS OCCURED, I HAVE LEARNED THAT GM WAS AWARE OF THIS PROBLEM FOR QUITE SOME TIME, AND ISSUED A RECALL FOR THIS PARTICULAR PART (PRESSURE SWICTH) AS WELL AS FOR THE DIVIDER VALVE. UPON CONTACTING THE LOCAL GM DEALER (DALLAS AUTOMOTIVE GROUP, JACKSON, OH.) I WAS INFORMADE THAT MY VEHICLE WAS NOT COVERED BY THIS RECALL. IN FACT, I WAS TOLD THAT IT ONLY APPLIED TO 2 VIN! FINDING IT HARD TO BELIEVE THAT A RECALL WAS ISSUED, BUT FOR ONLY 2 VEHICLES, I CONTACTED GM CUSTOMER ASSISTANCE. I TALKED WITH GREG MARTIN, CUSTOMER RELATIONS MANAGER, AND WAS INFRMAED THAT MY BUICK'S VIN WAS NOT AMONG THOSE COVERED. HOWEVER, ACCORDING TO THE GM SERVICE BULLETIN REGARDING THIS BRAKE PROBLEM, ALL PRESSURE SWITCHES THAT ARE BLACK IN COLOR ARE TO BE REPLACED, ALONG WITH THE "O' RING SEAL. IT FURTHER STATES THAT AFTER REPLACING THIS PART WITH THE GRAY REPLACEMENT PART, SERVICE PERSONELL SHOULD CHECK THE DIVIDER VALVE . IF IT IS CAST IRON, IT IS TO BE REPLACED WITH A BRASS VALVE. IN SPITE OF ALL THIS, THEY MAINTAIN THAT THIS VEHICLE IS NOT COVERED. FURTHER, THEY CLAIM THIS VEHICLE IS NOT EFFECTED EVEN THOUGH THE PART FAILED, AND DID SO IN THE EXACT MANNER DESCRIBED IN THE SERVICE BULLETIN. I BELIEVE THAT THEY ARE SIMPLY NOT HONORING THE RECALL BECAUSE I AM NOT THE ORIGINAL OWNER, AND DON'T HAVE THE ORIGINAL RECALL NOTICE. THEY ARE MERELY THUMBING THEIR CORPORATE NOSES AT THE SAFETY ISSUES INVOLVED IN TOTAL BRAKE SYSTEM FAILURES.*AK