Oopsy; OD fix almost worked.....HELP!

[Abner Mality]

I performed the odometer fix on my '80 300SD this past Wednesday. I followed the instructions as posted here in the group -- coat hanger, etc. Was able to clean up all the numerals, paint all my needles, and reassemble with only a few problems most of which were caused because my hands are really hams in disguise.

Upon completion, I did the requisite crowing, strutting, and back-patting until my better half blew the "okay, you're great" whistle, then I reinstalled the instrument cluster and hooked everything up.

That called for even more self-congratulation, and I then took to the road for a true test of my work. It was early in the test drive that my ego was deflated as I had no speedometer function. As I continued to drive on, it became apparent that neither the odometer nor the trip odometer worked, either.

The only positive is that the cluster looks much better, and the cruise still works. I take the latter to indicate the cable is driving the speed sensor as designed, so I have no cable problem.

Upon my return home, I went to the workbench to put away my tools and found one small, itty-bitty, white plastic gear on the towel that I had used to keep all the parts on the benchtop. This is a very small gear -- about 1/4 the size of a dime. I have no idea where it should go, but have to wonder if the gear missing from the speedo is the cause of my problem, or if MB just threw it in as an extra part. Whichever the case, I need some guidance before I remove everything and start over.

I suspect I will need a new or used speedo head, but if anyone has any suggestions that will, or might, save me that expense, I would appreciate your help.