i have very little brakes. i replaced the rear shoes, wheel cyl., had drums turned. still no brakes they wont bleed, constant air comeing through. traced brake lines back to master cyl. no leaks, bought one of those hand pump bleeders, it works realy good but air keeps coming. is it posible its leaking into the brake booster? the level in the resivoir dont drop. is it possible its sucking air through the plunger assembly? the peddle is hard, if you push real hard on the peddle the right rear will lock and you go slideing through the intersection, my wife dont like it.