IHave you everr wondered how it works? nside the motor are two electrical circuit connections to the wiper. One connectuon is a copper strip which is continuous, and the second copper circuit is the parking circuit. When one turns off the wiper at the switch, power continues to flow to the second copper circuit, and that circuit has a section where there is no copper and that is what parks the wipers. It is obviously at the wrong spot, but it should be possible to rotate the wheel inside the motor to the correct spot and then re-mount the wiper motor on the car. This is a good time to mention that there is a grounding strap that often becomes corroded and causes the wiper to stall out. I use a dedicated ground wire to the mounting bolts of the wiper motor from the battery ground, or where the ground wire fastens to the cylinder head.
I still have to old motor, so I may take it apart to see how it works and if I can get it to work correctly, keep it as a spare.