There could be two causes for the locked front brake. Front pistons are notorious for locking up after the cars have set for a period of time. The other would be the hoses, as you suspect. With age, they start to disintegrate inside, getting small flaps similar to fish scales. These flaps, depending upon which direction they break loose, act like check valves and can block fluid from going to the caliper, or returning from the caliper once pressure is applied. To identify the source of the problem, disconnect the brake line from the caliper. If it releases, it's the line. If not, it's the piston. Don't bother to rebuild the caliper. Just replace it.
