I replaced some clips on a hard to find track (Yamaha Bravo) a few years ago and swore I'd never do it again. It was a relatively expensive, laborious, and time consuming process. I found that the clips were missing because they had worn through. I bought a few clips and the proper tool for installing them. In the process of installing them, I found that nearly all of them needed to be replaced because they were either cracked, or nearly worn all the way through. So I ended up buying a bunch more clips and found that removing the old damaged ones wasn't easy.
Would I do it again? Yes, because Bravo tracks are nearly impossible to find. Would I do it on an Invader/Intruder track? Maybe...It depends on how many and if some need to be removed.
Be careful, a cracked clip can eat through slides in a big hurry...