I just dove into this project with the purpose of removing years of gunk making the switch sticky and nearly inoperable. After completing the task with success, I decided to search for a DIY and make one if there was not something already.

Nice job.

I would like to add that I also removed the handle from the center by sliding it up. This enabled me to better clean the valley under the handle and also push out the clear pin that transfers light from the bulb to the spot on the handle.

Cleaning the socket the pin rides in solved the sticky issue. A dab of silicone grease made it nice and smooth. Additionally, I added a dab of silicone (di-electric) grease to the end of the spring/pin assembly that rides in the center of the switch. This also gave it nice smooth return action when fully assembled.

An LED would certainly be the ticket for this job and a resistor in the harness would work just fine.

I will take mine apart again to do the LED upgrade once I have an idea which one to use.

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85 300D 3 pedal. Current project.
83 300TD (need rear wiper assembly dead or alive)
84 300SD Daily driver
85 300TD almost 400k miles and driven daily.
98 E300D *sold
86 300SDL *sold and made flawless 10 hour journey to new home.