Interesting drum brake problem

My bosses collection Lambo had to be driven around the block every 6 months (bad job eh? ) pulled into the complex to park it and the rear driver brake locks up. We had to drag that poor tire 70 feet to get it back into the garage. Got it on casters and pushed it back into its place and ordered a brake line. His mechanic cut the hose at both ends and got a nice blast of fluid when he cut the cylinder side. We then proceeded to slice this line until we came to the blockage. it was 10mm of solid rubber, the hose swelled up choking the passage and the cylinder didnt have the pressure to purge its fluid, but enough to lock the tire.
I had a brake shoe on my truck lose half of its lining and it was wedging, locking the brake but it would release properly.