urq odometer assembly question

[GaidosIII@aol.com]

All,
 I have my ur-quattro instrument panel in pieces here in front of me because
the odometer had stopped working. The basic problem was as I suspected. The
pin that holds the rotating numbers had slipped out from the side with the oxy
warning light spring action timer.
 Looking at it I cannot see what Audi used to keep this pin from sliding out.
The pin holding the trip has a nice little nut on the end put clearly that
isn't what was holding the odometer pin.
 Anyone know what is supposed to hold this pin in?
Thanks
Anton