Steering cylinder on left side of tractor. Now if you look closely at the chrome cylinder towards the tractor cab side end there should be a jubilee clip or some sort of squeezing mechanism as the cylinder is treaded on to the control mechanism. Now it could be that the chrome cylinder has treaded a little forward or backwards on to the control mechanism .Leading to steering be slightly off centre. So grab hold of the chrome and rotate a little and start tractor to see results. If I remember correctly when changing seals that it was 13 revolutions of the chrome cylinder to centre the steering. Over decade last time I,ve worked on those system but I believe this should cure the problem enjoy.