The rear windshield wiper on my 94 Explorer wouldn't work right. It would run a half cycle, the quit in the non-park position. Sometimes you could jiggle it and it would return to the "park" position. I fixed the problem myself with a little time and no cost. This is how:
Pull the rear wiper blade straight back to remove it. Remove the four "push pins" or "buttons" (older Explorers have screws) which hold the plastic cover to the top of the rear deck. This can be done carefully with a putty knife or similar tool. Pry up the bezel which surrounds the rear inside door lock. Remove the hidden Phillips screw inside. Remove the two Phillips screws which secure the inside strap. And remove the strap. Gently remove the plastic panel by sliding it towards the top of the liftgate.
Peel back the plastic inside cover enough to expose the motor. Disconnect the motor wires (3) and remove the motor by loosening the three Phillips screws.
Remove the plastic covers from the motor assembly -- a small circuit board is inside.
Remove the brush assembly which partially serves as a reversing device for the motor. There will be four beryllium copper brushes. This will expose a round circuit board which turns with the wiper shaft. This completes the reversing device. Mine was full of old hard grease which had come from the worm gear assembly. The excess hard grease would not allow the brushes to make contact with the round circuit board. Clean the old grease off with solvent and bench test. Put the motor back together and reinstall. I don't know what the dealer would have charged to replace the motor, but it would have been a lot more than I paid!
