windshield wiper motor

Ok, I got the new switch wired up correctly and the motor works fine(high/low and park when shut off)....until I actually connect to the wiper arms. When I turn the switch on, the blades will move to the up position and stop. I thought the connecting rods under the dash might be binding so I reached under and moved them a bit forward in their travel path and they go down and back up again to the top and stop again. They do not appear to be binding at all and the motor spins full circle without issue when not connected to wipers. What am I missing?