You may have bent the steering-arm on the box,or twisted the shaft.Set both wheels straight-ahead(by eye),then look at the steering-wheel position.Now sit on the cart,turn the wheel fully in one direction,counting the turns.Now turn it fully the other direction,counting the turns.Now split the number in half,this is your true-center.Turn the steering-wheel that amount,the wheels should be straight.If so,remove the steering-wheel and recenter it,if not,readjust the tie-rods.Are the wheels both turning the same amount,when you turn?There may be a bent steering-arm on a spindle as well.Hope this helps.
