If your gear that you bought and put into the transmission end isn't showing any sign of wear or even of the teeth of the drive gear touching it, then it almost has to be a problem with the drive gear in the transmission. I don't know how hard yours is to get to, but can you take a light and look inside the hole where the cable and gear goes and see your drive gear? As said above, unless you are a good transmission person, it would be best if the drive gear is the problem to take it to a transmission shop to have them replace it. Also you said with then old gear it just started jumping around. Have you tried putting the old gear back in and seeing if you get any resistance or it will turn at all?
Ron
