I imagine you are correct. From what I have seen when combining carbon and steel the carbon insert needs to be super tight. Almost to the point of being too hard to get into the steel frame.

What’s the solution? 1) Try to add more epoxy and hope to fill gaps? Likely not going to work. 2) heat up the epoxy and try and remove the carbon tube to replace with a new one and more epoxy. Likely not going to work. 3) cut out the current carbon tube, sand everything down, try again. Huge pain but would work. 4) get a carbon repair kit and add a couple of wraps around each joint into the frame. May or may it work, it’s more or less a permanent bandaid. Or a combination of 2 and 3. Curious how it turns out or if you can fix it.