Once you feel you've done these as good as can be expected, try to pull the turnout apart by gripping each end wrapped in a rag so as to minimize hand pain and Peco pain.
If this doesn't get the thing to come apart (about ½" is best) then get a very small screwdriver and pry the square metal doohickeys out of tie holes. You'll see them when the Peco is face down and you scope out the third tie from the end (points end)it has 2 big square holes in it. Be careful to not cause too much Peco pain; do not fold, spindle or mutilate. You may wiggle the track back and forth in the plane of the rails and stretch the Peco hard.