Suggestion as to repair as follows;
actually you can just buy the end gear (the one with the broken teeth) , open it up, and replace it. no need to replace the whole cluster -- nor the odo)
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The car is a 1994 SC2, the odometer has been intermittently failing for a while starting about 90,000 miles or so. Seems to be in part related to outside temperature and in part immediatly after re-setting trip odometer.
Note, the Speedometer portion is operational.
If the above suggestion is valid, it assumes that a drive cable some where (probably from the transmission or a front wheel take off) I havent looked so don't know for sure, has broken a drive gear. If that is true than the speedometer should also be in a failure mode.
However service literature indicates that the speedometer and odometer despite the standard analog appearance is actually digital and is driven by the >Vehical Speed Output Signal< a square wave or digital string of signals whose frequency is a function of speed and is generated by the Power Train Control module and enters the speedometer electronics as a >Speedo Signal<. This Speedometer Electronics is shown as then driving the speedometer module proper and the Odometer module.
This leads me to believe that the problem is still a function of the instrument panel or some portion of it anyway forcing me to still try to find a replacement for a 16 year old car that is no longer in production anywhere.
Suggestions or just thought provoking?

 

indeed the VSS signal drives the electronics which drive the speedo odo combo

My assumption was that the end gear had lost a tooth (stripped) which is not uncommon unfortunately. If this is the case then what I described will be sufficient.

From your continued description, it is probably not a stripped gear since if it was, it would not intermittently function ok

Sounds more like an issue with the electronics which drives the speedo odo