auto antenna mast replace- can't get it to rewind itself, AND RAIN IS ON THE WAY!!
 

I'm replacing my antenna that my wife left up while going through the carwash. I've got everything out and I'm ready to put it back in, but since it's an automatic, I don't know how to control the 'down'. Tried to get the mrs to turn on the radio and turn it off, but no luck. I know it runs, because I hit something while I was messing with it (cover plate off), and it started running. HELP! I'm about to get rained on, and I've got the antenna out of it's hole. Need QUICK HELP! Thanks! Lee Oh, yeah. It's an 81 300D. Hirschman auto

Antenna replacement
 

Since you don't have any answers yet, I'll try to help a bit. I recently replaced the antenna in my '93 Volvo 940. I'll assume the MBZ works the same. The replacement antenna mast has a toothed nylon "gear" hanging out the bottom. The teeth are to point toward the front of the car when the mast is installed.

First, turn on the radio. This will cause the motor in the antenna base to run to the "up" position.

Next, insert the toothed nylon gear into the antenna hole, teeth pointed forward. Push down until the gear stops.

Next, while pushing down on the mast, have someone turn off the radio. The antenna motor should turn on and try to retract the antenna. You push the antenna down and the motor's gear should grab the nylon gear and pull it down.

In my case, I had to cycle the antenna up and down twice until it completely retracted.

Then you tighten the nut at the top ot the antenna mount.

Where you might have a problem is if a piece of the old nylon gear broke off and remains inside of the antenna motor assembly. You can tell if this is the case by comparing the old and new nylon gears. If this happens, you must open up the part of the antenna motor assembly where the mast nylon gear winds up and remove the broken piece. This is what I had to do.

As I said at the start, this is the procedure for my Volvo antenna. I would guess that the MBZ is pretty similar. Good luck! If this doesn't work, cover the antenna hole until you get more help.