On February 2, 1996, about 1830 eastern standard time, a Beech C-45G, N204AA, collided with trees during a forced landing near Blountville, Tennessee. The airplane was operated by Saber Aviation, Inc. under the provisions of Title 14 CFR Part 91, and instrument flight rules (IFR). Instrument meteorological conditions prevailed. An IFR flight plan was filed for the positioning flight. There were minor injuries to the airline transport pilot, and the airplane was substantially damaged. Origination of the flight was Madison, Indiana, about 1700 on the same day. The pilot reported that as he overflew the Tri-Cities, Tennessee airport, at 9,000 feet, the right engine power slowly decreased, with the manifold pressure dropping from 28 inches to 25 inches. The airplane was in the clouds with an outside air temperature of about zero degrees Celsius. Right engine manifold heat was applied for a few seconds, with no noticeable difference in engine performance. The right magnetos were also checked with no obvious malfunctions noted. The left engine began to run roughly, manifold heat was applied to the left induction system and the roughness of the engine was eliminated. A descent for landing was initiated to the Tri-Cities airport. During the descent manifold heat was applied and removed several times, with no appreciable effect on the right engine. On short final approach, when the landing gear was extended, the right main gear did not indicate down. A go-around was initiated, during which the pilot discovered that the left manifold heat control was now stuck in the "ON" position. The pilot stated that with less than full power available on the left engine, and the right propeller unfeathered, the airplane could be climbed to about 200 feet. He flew the airplane until terrain clearance was no longer possible, then landed in a field, gear up. The airplane slid into trees and was substantially damaged.