From what I've come to understand, you do have the blower motor blues.
I'm still monitoring the ticking. It comes and goes. Sometimes it's gone completely, sometimes it's very minor, and very occasionally, it's really loud. I know it is wearing out, and I'm just waiting for it to become intolerable. Fwiw, if you're cruising on the highway, and have your radio up loud enough, it drowns out all but the worst ticking.
It seems the blower motors just wear out and need to be replaced. I have never heard of any other car make in my life that needs to go through blower motor replacements, like our wonderfully, German engineered blower motors do.
I bookmarked a website that was called "the poor mans Mercedes newsletter", that showed a guy pulling his blower motor out and replacing the brushes. The site doesn't work anymore.
I don't know if this is a good or even worthwhile project, as there may be things other than brushes that wear out.
Fwiw, the blower motor is under the windshield wiper assembly annd motor, and apears to be a job that's not too difficult, and may take 2-3 hours.
I've experimented a little with disassembly of the wiper unit to look at the blower motor, and it seems like a DIY'er could do it.
To take out the wiper motor, you first open the wiper arm cover, loosen the hexagon socket screw, and remove the wiper arm. You then unscrew the 4 hexagon nuts, take off the retaining clip, unplug the electrical connection, then take out the wiper system unit. Then, you'd unscrew the hexagon nut of the wiper motor shaft, take off the crank arm with the attached linkage, and then unscrew the wiper motor.
Once the wiper motor is out, you can see the cover for the blower motor. The cover appears to be held in by clips. You can also see the outside air temperature sensor that you'd have to unplug.
Once the cover is off, I don't know how the blower motor comes out. I know it must plug in somehow, I don't know if it simply plugs in or needs to be rewired. I'm guessing the motor justs rests in there somehow, and can be pulled out.
Maybe Gilly or Stevebfl, or someone whose done this can help us out...