I have a 2001 Mitsubishi Montero XLS with about 136,000 miles on it. I kept hearing a weird sharp sound even when I wasn't braking, then the ABS and Brake light came on. The brakes seem to be working pretty normal. I took it to the dealer and they said that I needed to replace the Brake Booster w/Accumulator Hydraulic unit which is about $1300. Does this sound like it could be that or could it be something else?