Ok I have more details figured out.
The bottom of the slug (the flat side) fused with the rubber grommet at some point. The nipple end of the slug was halfway inside the coil, and the coil housing and sleeve melted down in the middle of the coil, surrounding the nipple. I'm assuming because the back of the slug became stuck to the grommet.
I had to cut the top half the coil apart and unwind it because I couldn't get to the screws to get the slug out, because it was locked at both ends, fully extended downward. I also couldn't get in from the top of the coil hole in order to try to cut the melted plastic out, because it was just not possible. Especially while trying to save the rubber nipple which I wasn't sure if it was in tact or not.
Now that I have it out, I think I can just insert an audio equipment rubber wire grommet in the bottom stop where the flat end of the slug hits. But maybe the slug will just knock it out. Who knows.