On September 23, 1997, at approximately 1545 mountain daylight time, a Schwiezer SGS 1-34 glider, N7636, was substantially damaged following a landing overrun at Heber Valley Airport, near Heber City, Utah. The commercial pilot, sole occupant in the glider, was not injured. The glider was owned by Utah Soaring Association, Salt Lake City, Utah, and operated by the owner under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the personal local flight which originated approximately 1 hour, 45 minutes before the accident. No flight plan had been filed. According to the pilot, he "entered the pattern on a 45 degree diagonal intercept to the downwind leg of a left-hand pattern approach to runway 21." He stated that "I engaged the spoilers abeam the numbers on down wind." The pilot further reported that he used the spoilers on base leg and final approach, but "continued to float down the entire runway due to ground effect." The glider's center wheel bounced on the runway 2 or 3 times before the aircraft overran the runway and impacted an embankment and fence. The pilot reported in the NTSB's Pilot/Operator Aircraft Accident Report (form 6120.1/2) that "it appears that the spoilers were not extended." He stated that "it is possible that I was pulling on the spoiler engagement lever without depressing the button at the top of the lever which unlocks the spoilers." The pilot reported to the Investigator-In-Charge that he has 340 hours of flight time in aircraft, of which 25 hours is in gliders. The pilot further reported that he has 53 flights in gliders.