On July 20, 1999, at 1530 mountain daylight time, a Piper PA-18-150, N400MA, sustained substantial damage when it nosed over during an aborted takeoff from a private airstrip approximately 5 miles north of Lamar, Colorado. The commercial pilot/flight instructor/aircraft mechanic and sole occupant, was not injured. Visual meteorological conditions prevailed for this local area test flight operating under Title 14 CFR Part 91 and no flight plan was filed. According to the pilot, the flight was the first flight following replacement of the wing, and the aircraft had not flown in a (unspecified) "long time." In an interview, the pilot said the left brake locked during the takeoff roll and he initiated an abort. During this event, the aircraft nosed over and came to rest on its back damaging the lower cowl, spinner, propeller, windshield, left wing spar, right wing spar, both lift struts, and the rudder. Due to damage incurred during the accident event, no determination could be made as to the cause of the brake problem.