Ok. I have an auto box and have watched at close quarters while a friend and M-B technician uncoupled the speedo cable from the tranny, shot some lube up the speedo cable housing and reconnected it. There are a couple of steps that are probably germaine to an auto box only, like disconnecting the shifter rod from its lever to gain access to the pinch bolt, so I shouldn't cloud the waters with a total "step by step."
What may be common to both boxes is that the pinch bolt that secures the drive end of the cable is a metric allen headed bolt and needs an allen socket with at least a six inch long shaft to reach in tight quarters. The allen bolt must be removed completely to allow the cable end to be withdrawn, and there should be a rubber boot on the cable end to prevent debris from entering the connection. Withdraw the cable end, pull it up into the engine compartment so that you can shoot some engine oil into the cable sheath and patiently allow it to penetrate down the length of the cable. Then lower the cable back down the same path to the tranny where it formerly ran, and patiently allow excess fluid to drain out of the cable. You are not trying to drown the cable, just lube it up a bit!
Then carefully re-insert the cable end into its socket on the side of the tranny, being careful to seat the rubber boot and carefully hand-thread the allen bolt back into place. You can't thread the bolt if the cable end is not inserted fully or pushed in too far, but you can thread it in if the cable is not inserted far enough into the socket for the square drive tip of the cable to engage the drive gear in the transmission, so you need to check to see that you can't pull the cable end out if its socket after you have the bolt fully threaded but not tightened down. Don't use the socket drive handle until you are ready to snug up the threaded bolt.
That's it! I don't know the size of the allen head, maybe one of our tech gurus can chime in?
