It abruptly froze 1/3 of the way up last night. I see Benzes with stuck antennae like this on the road all the time -- is this a common problem? Any idea what causes it before I start pulling stuff out and checking voltages?

Clean you antenna with WD40....and check is the antenna switch on all the way position
not the half position (if you have antenna switch).
hope this help

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MB STARS Master Guild Technician,12 years MB tech
5 years independent shop owner

A good practice to get into is wiping your antenna everytime you fill-up your car with fuel.

I have purchased and use antenna wipes. Each package is about 1.5" square and when you tear off opposing sides, you can slide the whole packet over the extended antenna and repeatedly wipe it up and down. I believe that the "moisture" in the wipe is merely isopropyl alcohol. It is remarkable how dirty an extended antenna can get and that dirt can certainly affect the antenna's proper functioning.

I'm not sure if WD-40 is sticky enough that it may attract dirt while extended. As for the alcohol, it'll evaporate quickly and leave the antenna dry.

Good luck-

Terry

A bent mast will cause this. Just grab the bottom of the mast and rotate...you will see if it is bent. If so replace it. The mast can be bought seperately from the motor and is easy to install.

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Thanks for the help. I think it's an electrical or mechanical problem, not a dirty or stuck mast. It has always worked smoothly before. It can't be raised or lowered by hand, although it moves slightly then bounces back to the same position when really pressed. Seems to me that the gears or motor is frozen in place.