I converted my Firebird from manual brakes to power brakes (drums on all corners). The booster appears to be working until it gets down to the very end and then it feels almost like manual brakes. The brake pedal is hard so there does not appear to be any air in the system. I checked vacuum and it is 19 inHg at idle so that should be good. I don't see any evidence of the vacuum line collapsing when I brake. It appears to be a faulty booster but it is brand new. Any ideas?