On November 2, 2000, about 1200 Eastern Standard Time, a Cessna 177B, N35241, was substantially damaged after a forced landing near Prosperity, Pennsylvania. The certificated private pilot and pilot-rated passenger received minor injuries. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight conducted under 14 CFR Part 91. According to the pilot, he and the passenger were practicing maneuvers, for the commercial pilot practical test. While at an altitude of about 2,500 feet above the ground, the pilot heard a loud "pop," and the engine lost all power. The pilot made a force landing to a field. After touching down in the field, the airplane struck a fence and came to rest in briar bushes. The pilot did not report any prior mechanical difficulties with the airplane's engine. The airplane's magneto system, a Teledyne Continental Motors D-3000 Magneto Ignition system, was forwarded to Teledyne Mattituck Services Inc., Mattituck, New York, on January 10, 2001, and examined in the presence of a Federal Aviation Administration inspector. The inspector observed that both sets of points remained closed, regardless of the cam position, when the magneto system was tested. The inspector also stated that all securing hardware torque seals were intact and there was no evidence of point adjustment shifting. A Safety Board investigator examined the magneto system on February 7, 2001. As the impulse coupling was turned, the lobes of the cam would not push the cam follower far enough to open the points.