1982 300D White 200K+(?)

I forgot to mention how I fixed my tach with no tools. I also learned this from the MBZ.org site. I removed the sending unit under the drivers side hood on the fender by unscrewing by hand. You now must separate the screw cap from the sending unit. The video from repairFlix.com says you have to saw the top off, but I have done this with 3 different ones this week and needed only hand pressure to separate the top (this made me very popular at my MB club this weekend... fixed 2 of 3 tachs this way!!!)
With a bit of coaxing and twisting, the cover of the sending unit comes apart revealing a layer of white silicone stuff which protects the circuits.

The "fix" consists of placing a bit of sponge or foam in the cap (a cigarette filter was suggested...) thus providing extra pressure on the pins when screwed down. This fix may work for one of two reasons... either you have a cold solder joint under the silicone, or the contacts are improved by the pressure. Either way it will work or it won't.... Hope it does for you, it did for me.

Thank you all for listening.

Mr Goodfahrt