On June 8, 1995, at 1515 central daylight time, a Stokes, SMITH DSA-1, homebuilt airplane, N33BS, sustained substantial damage during a forced landing following a loss of engine power near Brookshire, Texas. The commercial pilot received minor injuries. Visual meteorological conditions prevailed for the local personal flight conducted under Title 14 CFR Part 91. During interviews, conducted by the Federal Aviation Administration (FAA) inspector, the pilot reported that after refueling, the flight departed a private airstrip near Waller, Texas, at 1525. A witness (statment enclosed) observed the airplane at 300 to 350 feet above the ground and "heard the aircraft mag cross firing." The pilot reported that the engine lost power. During the landing roll, the main gear hit a rice levee, the airplane cartwheeled and came to rest nose down. Horizontal stabilizer, vertical stabilizer, wing spars and engine components were damaged. A review of FAA records and the airplane maintenance logbooks revealed that the airplane was built by the current pilot/owner. Bendix model S4LN21 (P/N 10-51360-30) factory remanufactured left magneto (S/N 321336) and right magneto (S/N 321337) were installed on June 10, 1988. The airplanes's first flight was conducted on January 2, 1989, and on November 16, 1989, an FAA airworthiness certificate was issued without a geographic operation limitation. The builder holds an aircraft repairman certificate issued by the FAA on December 1, 1988. Records indicate that he performed the maintenance for N33BS including the last annual inspection on June 7, 1995. The magnetos were examined at C & D Aviation at Waller, Texas, and the FAA inspector reported that the teardown of the Bendix magnetos revealed that both magnetos had "heavily corroded coils." The left magneto coil "failed the resistance check." Ground lead to high tension resistance "read .85 ohm"; according to the manufacturer it should read "12,000 to 16,000 ohms." This was the pilot's "third forced landing due to engine failure" and prior troubleshooting by the builder did not lead to magneto teardown. Numerous attempts were made by the investigator-in-charge to obtain the Pilot/Operator Report (NTSB Form 6120.1/2). To date this report has not been received.