Take the cable off the back of the hour meter. Start the tractor and see if the cable turns. If it is not then you may need a plastic adapter in the drive end. Some of the replacement cables do not fit the drive correctly and use a plastic adapter/filler.
If it is turning then spin the tach/hour meter with your fingers and see if it bounces. If it does then the cable is not the right one for your hour meter. If it does not bounce than your hour meter is faulty.