My '82 has developed a problem where the rears seem not to function correctly. Front rotors, pads and rear drums, shoes and cylinders where replaces not too long ago. Now excessive pedal pressure is needed to lock up the fronts, while the rears seem just dawdle. The hand brake is week also. The servo, vacuum lines and non return valve are all working and pressure tested to prove they hold vacuum. Now wondering if the brake pressure regulator is crook or if the shoe compound is too hard?