Pretty much ever since I bought this car about 7 years ago it would make an eerrr sound when you pressed down the brake for the first time when I ould start it up in the morning. It sounds like a pump noise, not mechanical. Now it is just starting to get more pronounced. Its louder, and longer like eeeeerrrr, er er eeerrr. The brakes wor fine, I just don't get it. I have replaced the accumulator ball. The car has over 200,000 mi. Could it be the powermaster is starting to wear out??