drw, you are right it is the gag linkage that was out of adjustment. First, the box tube frame bar is supposed to be set at 16-1/2" above the ground when the 3-pt hitch is lowewred. Then the gag post should lean toward the cutter bar so it has 1/2" to 5/8" clearance under the inboard end...The book also shows an extender bracket on the gag chain for use with a 9' bar. Take care, Dick B
This is actually the solution. (And btw, my 9' mower does indeed have that extender bracket, as required).
Getting the gag post to lean forward was quite a chore. I had to remove all the cables just to get it to budge. Now to put it back together again without removing the clearance on the gag post.