So I just replaced the Master Cylinder, bench bled it fine, re-installed, used my Harbour Freight pnuematic power bleeder on the rear, no problems. Move to the front, and I can't get any fluid out of the lines! It has something to do with the proportional valve?, I tried to bleed it, but nothing. I am getting fluid to it, and that little pin under the rubber thing at the end of the valve is not moving, even when someone steps on the brake. I can force some fluid by pumping the pedal, but it just suck air back in the front bleeders when you let off. How do I move that proportional valve to bleed the front? Thanks!