This is a follow up to my previous post.
My speedometer stopped working on Thursday on my '86 300E. I checked the cable while I was driving and it was spinning. Today I took out the instrument cluster spinned the speedo and it is running, the odometer is working as well. Now what? Benzmac suggested it may be the plastic gears inside the tranny. Would it be a DIY job, does the transmission have to come off for this repair? Also is it possible that the end of the speedo where the cable joins it wears out and the cable just spinns inside of it. Because when I am driving the car I hear a whirring sound coming from behind the instrument panel.
But there is no movement at the speedo. Of course the sound was not there before the speedometer quit.
Thanks for your advice.

Alex