If he found media in the water heater, then the machine lost some of its resin, which would reduce its capacity. Did he check to make sure it was drawing brine? If it lost media then it should be determined why and also the amount lost should be replenished. Did he set the pressure back to 40/60? There is a guy here named Gary Slusser that specializes with that valve and i'm sure he will give you some good info on it.