I own a 93 MB 300E 2.8. The antenna motor works when I turn the radio on and off, but the antenna does not extend or descend. It was extended out when it lost movement. Is this a stripped antenna motor gear? I looked over other antenna question submits, but was not quite sure they covered my problem. Thanks.

Most likely, the nylon rod attached to the metal antenna is stripped.
Very easy to replace in about 10 minutes.
JackD

You might try this...
Stand next to the antenna when someone else turns off the radio and give the top of the antenna a little pop downward. If the antenna is just stuck because of grit or a slight bend it will move. It may just need a little cleaning and lube.