Interesting drum brake problem

After I get the front brakes done on my DD Caprice, I'll dig into this thing. I'll probably do a rebuild on the back brakes, I believe the front brakes have been rebuilt because they look clean, but I'll look at them just in case. I'll check and probably redo all the lines. It would seem it's a wheel cylinder problem, I looked at the springs, and they looked fine. While I'm at it, I'll stick a 4 barrel on it too.