[tmpusfugit]

There are several things that can cause a odometer to stop working shortly after replacing the drive gear besides the documented binding of the odometer drive drum referred to in the write up. Specifically:
1) drive gear being larger in diameter than the old gear, usually no more than .010-.015" larger. This leads to the worm gear on the stepper motor binding on the new drive gear shortly after installation. Solution is to place a thin washer under the stepper drive motor foot to lift it ever so slightly removing the bind on the worm/drive gear. I recommend just a slight amount of white grease on the worm to smooth things out a bit
2) the new drive gear is too tight on the shaft, or the shaft is rusty/clogged with old lube and debris, requires cleaning and in some cases a pass through the center hole of the gear with a proper sized drill bit.
3) the gear itself is too "long" meaning that when the e ring is installed it clamps down the gear and binds it up. The over all gear stack can be reduced in height with judicious application of a file to the end of the stack.
4) some of the gears have had "flash" on the backside from the molding process, I think the removal is covered in the write referred to by previous responses in this thread.

I have seen or had all these problems in the 14 or so odometers I have replaced gears in, so it is not unlikely that one of these is your problem more so than the of needing a washer in the drive drum assembly (never had to do that, yet)