On July 7, 1996, at 1030 central daylight time, a Cessna T210L, N761YL, owned and operated by a private owner, as a Title 14 CFR Part 91 instructional flight, was substantially damaged during landing roll near Terrell, Texas. Visual meteorological conditions prevailed, and a flight plan was not filed. The commercial flight instructor and private pilot rated student were not injured. The flight originated from Rockwall Municipal Airport, about 60 minutes before the accident. According to the private pilot, during the purchasing of the airplane, he found a pool of brake fluid under the left brake caliper. The seller of the airplane hired an A&P mechanic to repair the brake. During the repair of the brake, the mechanic manufactured a hydraulic brake line and installed it; however, he did not bleed the brake nor perform a landing gear retraction test. A second mechanic was hired to add brake fluid and bleed the brake. The private pilot had not flown in over four years. He hired the flight instructor to get him current and qualified in the airplane. The flight instructor was also an A&P mechanic, and he was requested to check out the airplane for maintenance defects. During taxi, the flight instructor determined the left brake needed further bleeding; however, it operated satisfactory, and no maintenance was performed prior to takeoff. After completing three touch and go landings at Terrell Municipal Airport, the private pilot flew the airplane to Air Park East Airport to correct all maintenance anomalies found during the flight. During the landing roll on runway 13, with the flight instructor manipulating the controls, the left brake failed. The airplane overran the departure end of the runway, and crossed a ditch separating the nose landing gear and damaging the firewall. Examination of the airplane by the FAA inspector revealed that the left brake line was fractured due to the improper routing, which resulted in chaffing during gear retraction.