Had the windshield snow over. When I started the truck the wipers returned to the bottom of the windshield only and no longer wipe. I can manually turn the wipers they are still linked, and there is still resistance telling me that the linkage and the motor is still connected - but they don't wipe? I find it odd they will shoot back down to the bottom of the windshield when I turn the power on, but they don't wipe. every now and then they will quiver, even if the wipers are set to off.