Nice TX 250, I have bought rebuild kits from the Polaris dealer that worked, they were for a late 80's early 90's ATV's. Have them show you the diagram and look for the same looking brake cylinder and it should be good. Basically all you need is the cup and O ring anyway. Also I use Dot 5 silicone brake fluid in mine, if you spill some it will not eat the paint and it does not attract moisture. Don't mix the two types, flush the Dot 3 out and refill with Dot 5.