it sounds to me like the problem is not that the motor won't park, but won't stop at all so maybe it is the pod switch to blame. Whenever I had a wiper that would not park it would simply stop at the point in its cycle where I shut it off, that was a different problem than you are describing though.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz