04 V70awd Insufficient brake boost

[686 Sport]

Bought the car with 117,000 on the odometer; records from 50,000 showed no brake problems, but there has never been what I would call adequate boost at the brake pedal.

Soon after purchase I replaced the front rotors with Brembos, with no change in braking effect noted. More recently, at 134,000, I replaced front pads - also with Brembos - and bled at each caliper until new fluid was flowing. Still no change was noted.

Just to make sure, I re-bled the rears and pulled the rear pads. Since they still have 5-6mm of material and the rotors are over 11mm, I just cleaned it all up, applied lube at the usual spots, and re-assembled. On the test drive, I could not get the ABS to engage on a dry road from about 40 miles per hour. Braking is straight and pedal force is linear, but it just requires very heavy pressure to slow down in anything like a hurry.

There are lots of deer around here; when one jumped in front of me last week, I hit the brakes at 25-30 miles per hour and ended up having to change lanes to avoid hitting it. Clearly something is not right.

As per a recent thread by dna316, I performed a static test of the electric vacuum pump: turned on ignition, applied brake, pump cycled on for a few seconds and then off; applied brake again, and pump cycled for a few more seconds. This leads me to suspect that the problem is in the booster unit.

Could someone please provide or link to a testing protocol to isolate the proper operation of the booster and master cylinder?

tia, 686Sport