[Zoomad75]

Over-tightening of the previous spring eye bolt can cause the sides of the spring mount to squeeze in just a little bit. Add a sleeve that's a touch long and it would be a bear to shove it in the mount without serious persuasion.

If that's the case, a porta-power would be the slick/quickest way to spread that mount out enough to slide the spring into it. But if you can't do that, you should be able to come up with a way to spread the sides apart enough to allow the spring eye to slide into it.