Speedometer Works But Odometer Does Not

[Morris Capers]

This is my first post on here and I've used the explorer forum countless times for all of my problems but I am at a stalemate. Out of the blue my 97 Explorer xlt 5.0 AWD odometer has stopped working with ~107000 miles. I thought that it was the worm gear, like many other people have delta with, so I bought a new one and replaced it. When I took apart the cluster I noticed that all of the gears were intact. The odemeter moves freely if I turned the gears, increasing the miles, by hand. I put the cluster back together and the odemeter started working again. It racked up about 400 miles then stopped again. I did not reset the trip odometer either. So I take the dash apart again... unplug the motor that turns the odometer plug it back in and to my surprise it is working again. I put it back together and this time it racks up about 250 to 300 miles then stops. I assumed it was the motor itself so I pulled several from a junkyard. I replaced my old motor with a new motor from a 97 mountaineer with a 80k on the clock and it worked for about 160 miles then I used a motor from a mazda b3000 or 4000 that only had 20k on it and it worked as well but stopped counting again. Both replacements and the original work and then dont and after being re-plugged in they work for a short time. I have came to the conclusion that it is not the gears or motors but I am not sure what the problem is.

Sorry if the post doesn't read well I'm typing on my phone in a bit of a rush