Naaa... I looked under the dash as I operated the switch and saw the defroster hose move when the arm stopped. Took the glove box out for access and saw where the arm had been contacting the duct... right on the seam. Took the arm loose from the motor, operated it by hand and saw where I needed to trim. Used a sharp wood chisel and removed a big enough V from the seam to clear the arm. Bingo.
The repop is 2 pieces sealed together leaving a 3/16 or so seam. The original was most likely metal with no seam. The repop fit the truck perfectly with pop rivets but that dastardly seam was in the way.
Soooo... if someone has repop ducts and the wipers stop at full cycle, look for interference with the trans arm.
