The first time this happened to me (gunk under ejector star that simply won't allow it to sit flush), I was completely blown away by how WRONG the entire revolver was while having the problem.
If you've never experienced this, it's an eye-opener. The fitting is monumentally precise. I had just enough crud under the ejector so that I could close the cylinder, but not easily or naturally, and it would bind up horribly. It was a sickening feeling, like something went HORRIBLY wrong and wasn't likely to be fixable. You only sit there and imagine WHAT you did, which part got warped or bent or what you may have "blasted" out of shape to almost kill your prized revolver.
Well, not only was there no "fixing" of anything and absolutely nothing broken or bent, it was simply getting the offending crud out of the way. So slight that with the untrained eye, you could never see anything wrong.
Cleaned it out and back to "bank vault" kind of lock up and function. Like a Smith & Wesson is supposed to feel like. Precision mechanical operation with all parts working in full harmony.
If you didn't realize how much needs to be "in order" to allow a quality revolver to function as well as it does, you will learn something the first time it happens to you. And you'll forever laugh, maybe just quietly inside, every time you see someone talking about the "will always work, can't be stopped, ain't never ever gonna malfunction" nature of a nice revolver.
Man, I absolutely -LOVE- my revolvers. But I know far better than to think they are simple devices that can't or won't ever "stop." I know that it just doesn't take much at all to really stop one, and it isn't a simple tap-rack-bang to get running again.