[rfeenstra]

that Bakelite can be in there a bit tight.  I've done a couple of these and 4 Mershons that are assembled the same way.  I use a belt sander to take the lip off.  I've found that you need to go a bit farther than what it appears that you did.  I think I can see a tiny bit of crimp left holding the Bakelite in tight.  Then, I put the nut on the threads and gently tighten it and even have put another nut on to give as much support to the Bakelite threads as possible.  I'm trying to distribute the forces of rocking and twisting the Bakelite plug away from the thread part and onto the plug itself.  A couple of them that I did took a lot of gentle working to break the corrosion before the plug came loose.  Once the plug is out, I drill a small hole through the Bakelite right next to the stud for the positive lead and another farther out for the negative.  I sand the edge of the plug so that the plug will seat farther into the can up to the narrow crimp section.  This allows me to roll the sanded edge of the can to re-crimp the plug.  Where the negative wire comes out, I indent the can slightly to accommodate  the negative wire which is then soldered to the negative terminal ring.  I'll also solder the wire to the can with a tiny solder connection.

A couple of pics here: https://philcoradio.com/phorum/showthread.php?tid=19313         You can see the edge of the plug I sanded to allow the plug to seat deeper in the can.  You can also see the edge of the can rolled in slightly to hold the plug.