Sean -

Super glue isn't strong enough to glue the plastic gear back 
together.  BTDT didn't work.  Use epoxy.  Here's the trick though.  
There should be a small hub on the gear.  Wrap the hub with string or heavy 
thread and wrap the hub with the string/thread embedding it in the 
epoxy.  Be VERY aware of where the epoxy cannot be so as to not 
interfere with the mechanism.  Multiple wraps with serve to tighten 
the hub against the shaft, so be sure it's in the right place.  Do 
both sides of the gear if the hub allows.

- Jeff  '80 Westi

> Thank you very much for the instructions.  You turned out to be right, I
> don't need to remove it (speedo face).  I was thinking I would need to remove the needle
> and the face to get easier access to the odometer mechanism but it turned
> out that I could remove the drive gear with no problem.
> 
> It turns out that my problem is that the drive gear is cracked.
> 
> Any ideas on the above are appreciated, including any ideas on a better way
> to fix it.