Hi Derek,

You could probably tell whether you have this feature by checking for the reset button/hole in the lower right of the cluster's face panel. That's where it is in US cars since 1990 brought us airbags. Before that, a lever protruded from the rear of the cluster to reset the service counter.

In this photo, you see the red cog at the 100's digit. The red cog is fixed to the shaft, where the blue and black ones freely turn. The shaft turns the white plastic gear at the left. That circuit board above it is there solely to provide the owner with a warning lamp at each oil change interval. The reset button lifts the driven gear from the worm so it springs back to zero.

I can imagine a gauge with no reset being done (bulb was removed, for example) would eventually drive that black gear to its limit of travel where it would then bind the shaft, and the red cog that drives from the 100's digit.



Here's another shot, from the side, showing the common problem where the spring dangles from its broken endpost. That spring is the one that holds those two gears in engagement. The black mechanism is an optical encoder driven by the white gear, pivoting at the bearing at its top. The "fix" is to remove it so the load is never presented to the odometer.


--
Art Benstein near Baltimore

Everyone seems normal until you get to know them.