I've got a 1998 sportsman 500 polaris and shifter is working OK will go in high low and reverse and go but it won't shift through gears in high or low never had any issues till it just quit automatically shifting not sure what to start with I changed fluid and basically that's it just been reading and searching for the problem and possible fix for it

 

Welcome to the forums.

Check out the Polaris section of the forums, they should be able to help you out.