I've just gone through this with a Heath S-119 receiver.
IMO, the answer is: no easy solution, and most likely things will turn out bad, i.e. cracked or stuck.
You don't want to use any liquid that will be asborbed. It seems the best recommendation I found was rubbing alcohol, which didn't help me at all.
In the end, 3 of 5 slugs were either cracked or cracked upon manipulation. Close inspection shows all of them were crumbling and deteriorating material. I bought an assortment of slug lengths from Nebraska Surplus Sales, no idea on mix.
https://www.surplussales.com/Inductors/Ind-SlugTu/Ind-SlugTu-6.htmlSlugs that moved partially turned out to be cracked and would shift and bind when rotated.
If excess wax is the problem a few moments application of a soldering pen may warm things enough to allow movement.
p.s. To add to the fun, I'm having to rewind two coils without any specs. This shifts circuit capacitance, so now I'm changing caps down the line.
![Smiley](http://amfone.net/Amforum/Smileys/classic/smiley.gif)