To add to what Tony said....

If at first you don't succeed- try, try again.

I have replaced four or five gears in the late model 240 odometers. One obviously showed a broken small gear and I replaced it with a new one from odometergears.com

However, when I reassembled the unit and drove the car the odometer still did not work. It was not because I had left behind a bit of the old gear.

I took it apart again and double checked everything: everything was in place and there appeared to be nothing amiss or binding.

Reassembly and road test still showed no odometer readings.

Took it apart again and had another look and still nothing seemed to be out of place. Carefully reassembled it once again and found that it worked just fine.

I do not have a clue as to what the problem was but persistance paid off.

So before you put all the trim back in place give it a quick road test to see if you have a working odometer.

... and remember that the gray wire with a red stripe is for a tachometer. If you do not have a tachometer don't attach it to anything- a number of clusters have been damaged by that mistake.

Good luck

Randy