It is not repairable, you should replace the instrument cluster.
Replace the instrument cluster.
You would fix it by replacing the instrument cluster. The speedometer itself may not be faulty, it is more likely to be a problem with the speed sensor.
These parts are only fixed by replacement.
You need to determine if it's the speedometer itself that's faulty, or the vehicle speed sensor. If the speedometer is faulty, you'll need to replace the instrument cluster.
You can't fix it till you know what's wrong with it.
Most likely speedometer cable
To fix a non-working speedometer and odometer in a 1998 Mercury Villager, first check the vehicle's fuse related to the instrument cluster, as a blown fuse can cause these components to fail. If the fuse is intact, inspect the vehicle's Vehicle Speed Sensor (VSS), which is responsible for sending speed data to the speedometer; it may need replacement if faulty. Additionally, examine the wiring and connections for any signs of damage or corrosion. If these steps do not resolve the issue, consider seeking professional diagnosis or repair for the instrument cluster itself.
There is no way to change gear ratios.
That would depend entirely on what's wrong with it.
Good luck, I've got the same issue
you have to get anew speedometer,speedy bo peep.
To fix an unsteady speedometer needle on a 1995 Mitsubishi Mighty Max, first check the speedometer cable for any damage or disconnection. If the cable appears intact, inspect the speedometer itself for wear or dirt that may affect its operation. Cleaning the speedometer mechanism with appropriate lubricant can sometimes resolve the issue. If problems persist, consider replacing the speedometer cable or the speedometer unit itself.