I have the 2-speed motor and my wipers won't "return" or park at all.
I've replaced the motor and still no luck.
Remove the screen on the drivers side cowl....and watch the action of the motor......does the motor "reverse" when you shut off the wipers?
If so, you have the correct motor and your problem will probably be in the cam assembly as mine was.
If you read thru the thread here there are lots of good ideas including making sure the switch is grounded well.
If you know the switch is grounding well, pull the linkage out and inspect the came assembly. Its not a complicated piece, but I found it has to be working perfectly to work at all correctly.
I also found that they work the best when the car is running (ie the battery is charging) ....as voltage drops, so does the performance of the system.
There is tons of great info from folks in this thread.....all of it came together and helped me see the bigger picture.....
Bruce was a HUGE help figuring this out as well! He is the guy who hooked me up with the parts I needed!
I posted a couple videos above that should help.....
Now, who has info on what exactly to do as far as tweaking the SS trim to fit flush with the windshield?? If I could get rid of the interference there, I could say its 100% fixed! Its 98% now....LOL