According to the pilot of the glider, on his second flight of the day, he initiated a spin to the right around 3,200 feet. After approximately three-quarters of a turn, the pilot attempted to recover from the spin by applying left rudder. The pilot stated that he felt no resistance upon application of the rudder, and that the glider was unresponsive. As he neared the ground, the pilot was able to maneuver toward trees. The glider impacted a tree, resulting in substantial damage to the wings. The glider remained in the tree for several days due to snow and ice storms before it could be recovered. Post accident examination by a Federal Aviation Administration Inspector revealed that the rudder turnbuckles were set per the manual and the rudder return springs were intact and not stretched. The rudder controls functioned properly when manipulated.