I would say you left out the drive gear, so that there is no connection between the cable and the speedo.
You really only need a little bit of LockTite to fix the odometer, just run some down to the zinc gear, wriggle the shaft back and forth to get it into the interface, wipe up all the rest of it (so the gears won't glue together, etc) and wait a couple minutes. All done.
I don't recommend that you disassemble the odo for this fix, it's way too much work!
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!