I had a problem a couple years ago with some NOS wheel cylinders. It was the weekend and I couldn't get replacement cups so I took a real fine scotch brite and cleaned the outside of the cups a bit. They were old and had gotten hard. I got them scuffed very lightly and worked some brake fluid into them and put them back together. I was able to get things working. I DID order new cups and when I got them I put them in. My patch got the truck moveable and would stop. Just a temporary patch job but might get you by in a pinch.
