HI Bill. Been following your efforts to get working front brakes on your OY. I experienced the same trouble with my truck, stripped the master cylinder cleaned it, bought new seals etc, had it off and on a dozen times with no more luck than you seem to be having. Finally gave up and bought a new unit from John Morter, fitted it and brakes all round straight away. Don't know what was wrong but couldn't get it to work on the front either. Best of luck. Rgs Ian