After the pilot selected the gear down, he observed that the single gear position indicator light indicated that the gear was down. During the landing roll, as the aircraft slowed down, the left wingtip and left propeller contacted the strip. Subsequent inspection of the aircraft revealed that the left main gear was in the up position. The left gear uplock bracket-block had recently been repaired but the forward hole had been drilled slightly off centre. This caused the bracket to tilt rearward and the block to slip off the uplock roller face and jam against the roller retaining bolt. When the gear was selected down the gear motor drove against the jammed uplock and bent the left retract rod. This allowed the motor to complete its extension cycle and indicate a gear down condition because the indicator switches are located on the activator housing and not at each gear leg.