The speedometer started not working well

Check to see if your cable is actually spinning when are ging forward. You don't need to go fast to do this. If it doesn't then take it out from thetop and check if it's not broken. Also you should pull your speedo gear from the trans. And check both the drive gear and driven gear. The drive gear will be on the output shaft of the trans. Just look to make sure everything is there. Both gears are plastic and are prone t breakage or stripping. If youreplace those they are color coded so if you have a white gear you need a another white gear otherwise your speedo will no t work correctly. Also if you have cable end that will fit in the speedo, mount that in a drill an drun the drill in reverse. That will show if your speedo is working. If it' doesn't then take it to a speedo repair place.