On June 21, 1994, at 1500 central daylight time, a Stinson 108-3, N6808M, registered to the Pete Hapka Seed Farm, nosed over during a landing on runway 30 at the Warren Municipal Airport, Warren, Minnesota, while on a personal flight. Visual meteorological conditions prevailed and no flight plan was filed. The airplane was substantially damaged and the pilot was not injured. The flight originated from Warren, Minnesota, on June 21, 1994. The pilot stated he was having problems with the brakes prior to takeoff. According to the pilot, the brakes locked up on touchdown which resulted in the airplane groundlooping and nosing over. The airplane was inspected by an Airframe and Powerplant mechanic who holds Inspection Authorization. He reported finding the parking brake set in the ON position in the cockpit. He also reported that skid marks were visible on the newly blacktopped runway. Two NTSB 6120.1/2 Forms were sent to the pilot to be completed. As of the date of this report, neither form has been received by the NTSB.