Hi. Having a problem with my brakes. Last time I bled the brakes was maybe 10 years ago. I have a dual master cylinder under the floor. Disc front, and drum rear. I have a adjustable proportioning valve and a line going to the rear drum brakes from the master cylinder. It seems to be leaking a little at the knob, and fittings on that adjustable valve. Can I replace that valve with a 10 Lb residual valve for the rear drums?? Thanks..