My Hirshmann was not working and the Mast was bent on my new-to-me W126 300SEL. The PO had disconnected the power and after re-connection the motor ran but would not engage the splined teeth on the mast replacement.

Upon disassembly and inspection there are 2 gears that are sandwiched together. One gear engages the motor drive and the other siamese-type gear drives the antenna mast toothed line.

They are coordinated by a tension spring that, I presume, is there allow for a bit of play between the 2 gears. My guess is this is done to prevent stripping the teeth on the mast tail if the antenna gets stuck or bent.

Both gears have a tab that ride in the same pocket of the spring. One of the tabs was broken.

I thought about fixing it with epoxy but felt that solution was likely not to hold for very long.

Instead I made a small aluminum tab that I riveted to the gear.

I used 1/2 in aluminum round bar, and a 5/32 x 1/2 inch rivet. I cut the bar with a jigsaw and shaped it to match the tab on a belt grinder.

I fount that an 8mm tall tooth left enough clearance for the head of the rivet.
Here are the pictures.

Hopefully it will last.

You can see the broken tab stuck in the spring in this first picture.

Untitled by ttownthomas, on Flickr
Untitled by ttownthomas, on Flickr
Untitled by ttownthomas, on Flickr
Untitled by ttownthomas, on Flickr
Untitled by ttownthomas, on Flickr

Thank you for sharing.

I did the similar thing, but I used the end of the stock of a toothbrush. Drilled a hole through it. Used a flat head screw on the outside with a counter sunk screw on the inside. Going on 5 years with mine...

All the best,

Martin