Here is a picture of screw removed.

Unplug the relay

Sorry, wjm. Its an 87 300e.
The hex nut is the one next to the speedo cable, right?
How did you get a rachet head to fit over it? With that out I'll remove the plug on the bottom of the relay & go to work w/the knives, is that correct? Or attack the firewall as Kamal did if necessary? Yes?

Use butter knives to remove the circuitry

Here is everything reinstalled.

In this picture you'll see what it looks like in my new installation. I replaced the buzzer with a Sonalert Chime.

wjm, I think on the 94 MB moved the hexnut a little to help out. Mine has less top clearance & I probably need the wrench. So the relay sits below that black thing & is reached by tilting up after unscrewing. The pics, worth a 1,000 words, as they say. Thanks again.

Rich,

I don't have a speedo cable in my 94, so I cant tell you. I think my picture should help with the screw I'm talking about.

The rachet head does not fit over it 100%... but certaily enough to get it off.

Once removed, the 2 relays will move enough to help with removal. Should have more than enough room to get the butter knives in.

Again, I've never taken out the entire relay.

As you said, your model year is a bit different, but with the right tool, you should be able to get that screw out.

10 mm hex nut cannot be seen due to presence of padding. two relay brakets are held by the two nuts one is 8mm and second one not visible is 10mm. 8mm is nut is easy to remove. but 10mm nut is removed by using extention and feeling the nut. There is not way you can see that because itz way back. 6" or longer extension will do the job. once you have bracket out then it is easy task. remove the relays using small 8mm nut(this 8mm nut is that hold relays in bracket) and replace with new one. While I was changing the relay, I droppped 10mm nut in back. I didn't bother to put that back. I only used the 8mm nut to hold the relay braket in place. I have pic at home that i will post that later.

It's Done!!
 

I did it this morning. Not too difficult, thanks to Willy's pictures. On the 87 300e the 8mm hexnut is a little lower & was easily removed with a hand driver, & I decided to avoid the butter knives & go for the firewall 10mm. I replaced the relay since it was only another 8mm, which was accessible. Dropped the 10mm once, but was lucky enough to get it out, then I packed paper towel into the ratchet socket & topped with 2-sided scotch tape to hold the screw while I inserted the extension. Worked like a charm, & now I have light. Thanks again Willy & Kamal.
Regards
Rich

Great news!

In my 94, it just not seem to be as easy as yours.

Oh, now that you have the old one out, take it apart. I bet you can see where the PCB board is damage/burnt out. I fixed mine by simply soldering a jumper wire.

If fixed, you can then experiment and change the nasty buzzer with a chime.

Willy

Willy, I planned to do that but didnt have time today. I shook the relay & it sounded like something broke off inside. I'll report back.
Rich