I replaced the push rod for a stock manual brake rod, stock backing plate,I retained the stock power brake proportioning valve and stock master cylinder. I bled the brakes front and rear, O.K. After said and done My front two calipers locked to the rotors and will not release unless I open up a bleeder screw. What is the problem now ? I have a line lock connected, working fine. 73 challenger, Thanks to all for your help.