As a last resort if all else fails blow compressed air through the lines. Then follow that with a brake fluid flush. Since the hoses are on it, plug the end of the a rear hose with a 3/16" inverted flare plug so all the fluid is directed out other side, then swap the sides with the plug. Catch the fluid in a bottle so you can see it when it becomes clear. The flare thread of our cars is 10mm X 1.0 but a plug in that size is impossible to find. The 3/16" is slightly smaller and screws in easy by hand and will seal the hose. If the old hoses are going to be replaced then just clamp them with vice grips.