Do as you will, but replacing just one part of the sprag is usually a bad idea. They typically don't last that well. A sprag failure in a UCE is not a common event. It is also one heck of a lot easier to replace, The newer the part and the more certain you are of its heritage the better, There are some BS sprags out there. I can't tell you how to tell other than to be careful of your source. The reasons for a sprag failure in a UCE bike it totally different than the failure in an iron barrel or an AVL.