In the tranny no. In your speedometer cable, or the odometer itself, yes.
The speedometer cable is easy to pull, inspect, clean, and relube with dry graphite powder. The Odometer may require disassembly of the dash to get to, and a used one to replace it with, as I doubt you will find any one to repair what you have.
It could be the nylon plastic gear set in the transmission that drives the cable that is going bad; as plastic does wear. You can replace them with aluminum gears out of a pick-up truck or another set of plastic ones but it requires removing the tail housing to get to the drive gear.