The strip being used was aligned southeast and the wind of 15 knots was swinging from southeast to southwest. On the second takeoff for the day acceleration was sluggish and the pilot kept the main wheels in contact with the strip surface for longer than normal before allowing the aircraft to become airborne. Shortly after lift off the aircraft mushed and the wheels contacted the ground. The pilot abandoned the takeoff attempt and the aircraft came to rest 240 metres beyond the end of the strip after sustaining damage to the left wing and landing gear. The pilot had limited experience on the type and did not appreciate that the engine was not developing full power during the take-off attempt. The mixture control cable outer sheath was found to be broken, in such a position that it could randomly prevent full travel of the mixture control, with consequent reduction of fuel flow to the engine.