Evan,
did you get the clicking noise fixed? There is another post here that discusses stepper motors failing too. Something about 10 servos requiring replacement and two days to do it.
My w203 has the exact same problem. I think it started gradually with faint clicking noises over the past year growing steadily in volume to the point now there is a loud thumping noise under the left of center dash location. Sounds like a linkage has "separated" and is impacting.
