1967 odometer just quit working, speedo and tach are fine, any clues to problem or fix?

if the speedo is working,i would think that something in the gauge cluster has broken

Had Speedometer Service, Roswell Ga....rebuild/repair the odo in my 66...my speedo worked fine also.....same situation..poor design>>> the odo worm gear fails...initially made of bronze ..the replacments are plastic.....my odo rebuilt 3 years ago still working....great price think it was 110 bucks for repair nice peple . Speddometer repair ser tel number tel 1-800-241-2385