I have lamented the sloppy fit of the miter gauge on my Ryobi saw. I found a $2.00 solution. My wife has a roll of something called Peel N Stick Fabric Fuse tape. It is shiny (and slippery) on one side and sticky on the other. It is 5/8 in. wide and fits the track perfectly AND makes the gauge move smoothly without sliding side to side as much as before.
Not a perfect solution, but a marked inprovement