I have tried a number of frustrating methods to remove the broken slug - all
to no avail. I did repair a number of slugs in the HQ-145. I ended up
making new coils with new forms and new slugs.

But, I think Chuck has the right and only approach. The problem is that the
core breaks and acts as a cam. Once someone tries too hard, bits fall off
the slug which will cinch the destruction. But, if before any particles end
up between the core and the threaded form, the super glue can be used to
secure the core enough to preventing it from "camming", then the core can be
removed. Once it is removed, I think it can be glued properly with
superglue. If you decide to use a different core, it must be the same
material - not just the same thread.

I think I would probably illuminate a led and insert it into the bottom of
the core and press on the form just before using the superglue to center the
core.

The core may actually be more unreplaceable than the form. In some cases it
might be a good choice to destroy the form to save the core - then glue the
core fully and make a new form. It is possible to get a form slightly
larger and use hot melt to create threads for the core. Something like a
large straw might work as a form.

73, Colin K7FM