A common problem is that the wipers don’t park. In this system the motor has to reverse to park the wipers. Often the issue is the mechanical nylon cam arrangement sticks due to old hard grease.

The electrical switch itself (black box riveted to plate) is quite rugged. I spent days on this only to discover the cam was stuck. The wiper motor and gears were also perfect. If you are having a problem with wiper park, check first for a sticking nylon cam.

From the factory service manual:
Disassembly: The wiper motor should be operated and shut off by turning off the ignition key. The motor must not be disassembled when the blades are in the park position or damage to the motor switch and contact follower will occur when the cover is removed.
(Information on the wiper motor system is under the "Electrical and Instruments" section of the service manual.)

I had found by accident that running the motor loose on the bench, even using the switch and running 12V to the switch and grounding the motor, this will burn out the motor quickly. I had an ammeter on it and saw a huge draw. The reason is the field winding completes to ground through the switch, through the switch mechanical mount to dash. Read more about this here.