So far as I know, all wiper motors get "park" via a 12v hot lead to the motor, which goes through and internal switch in the motor. Either the motor is not getting the 12V "hot" wire, or the internal park switch is bad.
i don't know. it doesn't seem to have specific speeds. this may be the switch but it seems like it is infinitely adjustable. as i turn it counterclockwise the wipers speed up with no detente feel. how can i identify what i have?