Do you have a
nautilus 2? I'm just guessing... did the coil become loose and wind up stuck in the chimney? And now you can't screw it back together?
That occasionally happens with the N2 and you need to remove it from the chimney (I find hemostats to work well, for grabbing on to the coil and twisting it out, without damaging the coil). Then, screw it into the base as usual. A hair tighter than finger tight. If you dropped the mod, you may want to check the chimney and that it hasn't shifted. That happened to me with one of my
nautilus 2s, and I was able to sort of "twist" it back into its usual shape.
I'm afraid I don't know for sure, but based on your question, I figured it might be a Nautilus 2 and that may have been what has happened.
With that said, without knowing more about your equipment (and if you can, perhaps post a picture, too) this is just a guess on my part. Welcome to ECF and best of luck. If the "solution" I offered above is not correct, please post more about the name of your equipment and a pic if you can.
Anna