On July 20, 1997, at 1500 central daylight time, a Schweizer SGS 2-8 (glider), N79106, sustained substantial damage during a takeoff attempt from runway 18 (1,865' x 100' dry/turf), near Menominee Falls, Wisconsin. The pilot received serious injuries. A winch tow was being conducted when the accident occurred. The personal 14 CFR Part 91 flight was being conducted in visual meteorological conditions. No flight plan was on file. The local flight was originating at the time of the accident. The pilot said that during the winch launch, the glider became airborne; however, when he increased the angle of attack, the airspeed decreased, and the glider entered a stall/spin. He said this occurred from about 100 feet above the ground and he was unable to recover prior to impact. The pilot stated that the winch used for the launch failed. He thought that the "most likely" problem was with the automatic transmission. A post accident examination revealed that when weight drag (weight) was applied to the winch cable, the automatic transmission slipped and would not reel in the cable.