wiper motor park intermitent

69 Barracuda variable speed wipers. Sometimes (5% of the time), the park feature works. Most of the time, when I turn the wipers off they stop right away- so I have to time it so that they are not in my vision. Other times, when they have been off for a while ( a minute to a day) they will swipe once and then 'park' correctly.

Ideas? Where do I look for the fix? Is this most likely in the switch or in the motor?