I knocked one back to center by taking a cheap drill bit that fit in the back ( rear) line opening and simply tapped with a claw hammer on the protruding bit end I'm thinking the bit was 5/64 or some such size when it moved like point 25 fluid would then fluid go to back wheels and bleed.My methods of bleeding use a lite touch on the pedal (during bleeding)to avoid knocking the proprtioner into shut off...as un stomping lol"I guess it only strokes a tiny bit, so you just shove something pointy in there to wiggle it back to the middle.