I don't know how you make straight bales with a JD! lol  We ran over a 100K through ours in the time we had it.  Always driving looking behing you to count strokes per bale and always resetting the fork position.  Set it, bale an hour, reset it, bale another hour and it would change again.  Get in a thick windrow, start putting 12 strokes per bale and they would be crooked, get in a light one and put 18 per bale and it would be crooked, but the other way.  This was in bermuda grass hay, normally 50-60 sometimes 80 bales to the acre, raked with either a Vermeer twin rake or a 10 wheel V-rake.  NH can make a crooked bale as well, but,,,,, is more forgiving to changing windrow size in our conditions.