I have done this on a similar kind of odometer--the one for the
78-245DL.
What you have to do is to locate the center shaft for the odometer
wheels. When you find that shaft, you will see that you can withdraw
the shaft if you remove the swage on the end of the shaft. I use the
term "swage" because I think that is the correct term for deforming
metal to make a catch or stop. Anyway you will find that the shaft has
been made out of round by the swage. You will need to file off the
swage with a miniature file whilst trying to keep all the filings out of
the odometer and speedometer mechanism.
After you remove the out of round swage from the shaft, you can push the
shaft out of the boss that holds it. You do not need to remove the
shaft so far as to have the odometer wheels fall off the shaft. All you
need to do is to move the shaft out of the boss and then you can make
enough free play in the shaft to move the number wheels away from their
drivers to adjust the three or four most significant digit wheels with a
tooth pick. You probably would need to move the shaft more (and dislodge
a digit wheel or two) to fix all digits, but it probably isn't worth the
effort. Once you have set the wheels correctly, mate them up with the
driving gears and push the shaft back through the boss. Fix the shaft
so it doesn't move with a little dab of wifey's fingernail polish.
There are legalities involved in changing odometer settings. For the
most part, I think that the law uses words like "tampering" and
"fradulently setting the odometer". I think you are in the clear if you
are actually correcting the odometer setting to a correct (or more
accurate) setting, without the intent to defraud.
