Drum Brakes Sticking

Between me and my uncle, we pressed the brakes and felt the drum tighten up like no other. Once we got it off and back on it was like normal. Then pressure and drum wouldn't move.

My uncle is guessing it's the line i believe he clamped it shut and unclamped it to come to that conclusion. We checked the metal parts of the lines on the car and no leaks or damage. The rubber hose coming to the wheel cylinder might be damaged or clogged inside?

Also it's a 1973 Plymouth Valiant Slant Six 225. The Emergency brake hasn't worked since i've owned it [another item on the checklist to fix]