I rebuilt an AX 15 in a 99 Wrangler.  It went back together fine, it shifts tight, only 1 problem.  Shifting from 2nd to 3rd is fine and from 3rd to 4th is good.  I just can't get it to go from 4th to third.  I am guessing it may be a ball or shift plug out of place in the rail or intermediate plate.  Any thoughts?   Thanks   Tim