Take antenna apart to install??
 

So far,no luck in searching the forum for my problem. I bought a Hirschmann antenna motor to replace the original in my '90 300E sedan. PROBLEM: I can't remove the screw-on nut near the top of the mast(so i can push the antenna up,through the grommet,from inside the trunk).The small rounded cap at the very tip of the mast prevents the removal of that nut. Do you have to remove the mast and wire in order to do the install?? Totally lost! Thanks for any help!!

I think you just unbolt the whole power unit from inside the trunk, then kind of wiggle it out. If the mast is stuck halfway up, you will have to break it to get it out of the car.

Its been years since I have done it, but I remember it being pretty easy.

I'm trying to install the antenna,not remove it.

I looked high and low throughout the Internet looking for the same solution to this problem with my Hirschmann 6000el.
I resolved this dilemma by taking the antenna out of the car and breaking the antenna in half.
Looking closely at the mast (after sliding out the corroded antenna) and exploded diagrams I can see that there is a metal sleeve within the plastic nub and that spun around with the nut.
I got the idea of pressing a drill bit against the side to create a channel. I looked at the length of the threads on the new antenna as a guide. Once the channel was made I took a jewellers screwdriver to bend back the locking nut until it fell out. Hallelujah!

I just refurbished my dead 6000 antenna, new circuit board, new mast, new seal, wiring was corroded - and yes you need to remove the mast before installling the antenna in the rubber seal on the car. Use battery power to raise the mast and undo the nut.