On January 17, 1997, about 0654 eastern daylight time, a Piper PA-32-300, N2816M, registered to J & J Partnership, collided with trees while making a forced landing following loss of engine power, at Boca Raton, Florida, while on a Title 14 CFR Part 91 personnel flight. Visual meteorological conditions prevailed at the time and an instrument flight rules flight plan was filed. The aircraft received substantial damage and the private-rated pilot received minor injuries. The flight originated from Pompano Beach, Florida, the same day, about 0650. The pilot stated that while climbing through 2,000 feet, after takeoff, the engine quit abruptly. Attempts to restart the engine were unsuccessful and a forced landing was made on a golf course. During the forced landing the aircraft collided with trees. Postcrash examination of the engine showed the left magneto would not rotate after removal from the engine. The crankshaft gear had three teeth broken off and had come loose from the crankshaft. The crankshaft idler gear to the left magneto had two teeth broken. No other evidence of failure or malfunction was found within the engine, engine accessories, propeller, or propeller governor. Examination of the left magneto, under FAA supervision, was conducted at Teledyne Continental Motors. The examination showed the rotating magnet was making contact with the magneto case. Scoring, galling, and blacking had occurred on the surfaces of the case and rotating magnet where contact was made. Metallurgical examination conducted by Teledyne Continental showed no evidence of foreign material in the area of contact. Installation of another rotating magnet into the case showed the magnet rotated normally. The exact defect with the rotating magnet was not determined. (See the attached Teledyne Continental report). Metallurgical examination of the crankshaft gear and crankshaft idler gear was conducted by Lycoming Engines. The examination showed each of the teeth separated due to overload breakage or sudden impact overload. (See the attached Lycoming report). Logbook records and maintenance work orders showed the left magneto was installed on the aircraft on December 30, 1996, 2.3 flight hours before the accident. The magneto had been overhauled on September 18, 1996, and had not accumulated any operating time since overhaul. The magneto that was removed, was removed due to it being inoperative. (See the attached logbook records and work orders).